Optical laminate

ABSTRACT

The present disclosure relates to an optical laminate or a reddening-resistant layer. The present disclosure can provide an optical laminate that does not cause a so-called reddening phenomenon even when driven or maintained under extremely harsh conditions (e.g., very high temperature conditions), or a reddening-resistant layer applied thereto.

This application is a National Phase entry pursuant to 35 U.S.C. § 371of International Application No. PCT/KR2020/001465, filed Jan. 31, 2020,and claims the benefit of and priority to Korean Patent Application No.10-2019-0037447, filed on Mar. 29, 2019, the disclosures of which arehereby incorporated by reference in their entirety for all purposes asif fully set forth herein.

TECHNICAL FIELD

The present application relates to an optical laminate or a porouslayer.

BACKGROUND ART

Increasingly, display devices are driven and/or maintained in harsherconditions. For example, display devices used for navigation devices, orvehicle displays such as vehicle dashboards are maintained and/or drivenat a very high temperature in summer.

Depending on the use of the display device, an optical laminate such asa polarizing plate may be used in contact with a glass substrate calleda cover glass. Generally, the cover glass or the like has excellentthermal conductive characteristics as compared to the optical laminate.Thus, heat is better transferred to the optical laminate in contact withthe cover glass.

Accordingly, the optical laminate such as the polarizing plate is alsorequired to maintain durability under much harsher conditions thanconventional ones (particularly, conditions maintained at asignificantly higher temperature than conventional ones).

DISCLOSURE Technical Problem

The present application provides a reddening-resistant layer, an opticallaminate and a display device.

Technical Solution

Among physical properties referred to in this specification, thephysical properties that the measurement temperature and/or themeasurement pressure affect the results are the results measured at roomtemperature and/or normal pressure, unless otherwise specified.

The term room temperature is a natural temperature without warming andcooling, which means, for example, any one temperature in a range of 10°C. to 30° C., or a temperature of 23° C. or about 25° C. or so. In thisspecification, the unit of temperature is ° C., unless otherwisespecified.

The term normal pressure is a natural pressure without pressurizing anddepressurizing, which means, usually, about 1 atm or so of atmosphericpressure.

In this specification, the physical properties in which the measurementhumidity affects the results are physical properties measured at naturalhumidity which is not separately controlled at the room temperature andnormal pressure state, unless otherwise specified.

The present application relates to an optical laminate, a display deviceor a reddening-resistant layer. The optical laminate or display devicemay comprise the reddening-resistant layer. In the present application,the term reddening-resistant layer may mean all kinds of layers thatthey are applied to various optical laminates including opticalfunctional layers to be capable of preventing, alleviating, reducing,suppressing and/or delaying the reddening of the optical laminates orthe optical functional layers applied to the optical laminates. Inparticular, even when the optical functional layer, which is very weakto heat, such as a polarizing layer to be described below (inparticular, an iodine-based polarizing layer) is used and maintainedunder extremely harsh conditions such as a high temperature, thereddening-resistant layer may effectively prevent, alleviate, reduce,suppress and/or delay the reddening of the optical functional layer.

The reddening means a phenomenon in which the optical laminate or theoptical functional layer changes red. The occurrence of reddening can beconfirmed, for example, through the a* value of the so-called CIE L*a*b*color space. In the CIE L*a*b* color space, the increase of the a* valuein the positive direction means that the object becomes redder. Inaddition, it means that as the absolute value of the a* value in thenegative direction increases, the object becomes greener. Therefore, thefact that the a* value change of the optical functional layer or theoptical laminate increases in the positive direction relative to theinitial a* value means that the optical functional layer or the opticallaminate has been reddened.

In the present application, the term reddening-resistant layer may meanall kinds of layers that they are applied to optical laminates orapplied together with optical functional layers to be capable ofpreventing, alleviating, reducing, suppressing and/or delaying the a*value change or increase of the optical laminates and/or the opticalfunctional layers in a positive direction.

The reddening easily occurs mainly when heat is applied to the opticallaminate and/or the optical functional layer, and therefore, thereddening occurs easily as the optical laminate and/or the opticalfunctional layer is maintained at a high temperature.

In the present application, the term reddening-resistant layer may referto a layer that after a heat-proof test the optical laminate or theoptical functional layer may have an absolute value of 2 or less in thea* value change amount. The heat-proof test means a test for maintainingthe optical laminate and/or the optical functional layer at about 95° C.for about 750 hours or so or at about 105° C. for about 250 hours. Thea* value change amount may be a value (a*_(a)−a*_(i)) obtained bysubtracting the a* value (initial a* value) (a*_(i)) before theheat-proof test from the a* value (a*_(a)) after the heat-proof test, orconversely, may be a value (a*_(i)−a*_(a)) obtained by subtracting thea* value (a*_(a)) after the heat-proof test from the initial a* value(the a*_(i)). In light of the purpose of the reddening-resistant layer,the a* value change amount may be a value (a*_(a)−a*_(i)) obtained bysubtracting the initial a* value (a*_(i)) from the a* value (a*_(a))after the heat-proof test.

The heat-proof test may be a heat-proof test performed under harsherconditions than a usual heat-proof test. For example, the heat-prooftest may be a heat-proof test performed in a state where the upper andlower surfaces (for example, the upper whole surface and lower wholesurface) of the optical laminate and/or the optical functional layer arein contact with a glass substrate. The glass substrate is a materialthat heat transfer is generally good as compared with an opticallaminate or an optical functional layer, and thus when the heat-prooftest is performed in a state of being in contact with the glasssubstrate, the influence of the applied heat on the optical laminateand/or the optical functional layer becomes larger. The type of glasssubstrate applied to the heat-proof test is not particularly limited,but in this specification, it is based on the application of a soda limeglass substrate having a thickness of approximately 1.1 mm. The glasssubstrate is generally known to have a thermal conductivity of about 0.6W/mK to 1.38 W/mK, where the optical laminate or optical functionallayer of the present application can prevent, alleviate, reduce,suppress and/or delay the reddening even when the heat-proof test isperformed in a state that the glass substrate having a high thermalconductivity as above is in contact therewith. Color coordinates and/ortransmittance values related to the heat-proof test referred to hereinare based on the application of a soda lime glass having a thickness of1.1 mm or so, where in the heat-proof test, the contact may mean a statethat the optical functional layer or the optical laminate comprising thesame is in direct contact with the glass substrate (soda lime glassplate having a thickness of 1.1 mm or so).

The optical laminate of this application may comprise an opticalfunctional layer; and the reddening-resistant layer formed on at leastone surface of the optical functional layer. As the optical laminatecomprises the reddening-resistant layer, the reddening of the opticallaminate or the optical functional layer can be prevented, alleviated,reduced, suppressed and/or delayed.

For example, for the optical laminate or the optical functional layerincluded therein the absolute value of the change amount (Δa*) in colorcoordinate a* values of CIE L*a*b* according to Equation 1 below after aheat-proof test may be within 2. The color coordinates referred to inthe present application are the results measured using a JASCO V-7100spectrophotometer.

Δa*=a* _(a) −a* _(i)  [Equation 1]

In Equation 1, Δa* is the change amount of the color coordinate a*,a*_(a) is the color coordinate a* value after the heat-proof test, anda*_(i) is the color coordinate a* value (initial a* value) before theheat-proof test.

In another example, the absolute value of the change amount (Δa*) mayalso be within about 1.9, within about 1.8, within about 1.7, withinabout 1.6, within about 1.5, within about 1.4, within about 1.3, withinabout 1.2, within about 1.1, within about 1.0, within about 0.9, withinabout 0.8, within about 0.7, within about 0.6, within about 0.5, withinabout 0.4, within about 0.3, within about 0.2, or within about 0.1. Thelower limit value is not limited because the absolute value of thechange amount (Δa*) means that the lower the value, the less thereddening occurs. In one example, the absolute value of the changeamount (Δa*) may be 0 or more. In an example, the absolute value of thechange amount (Δa*) may be a change amount when the a* value changes inthe positive direction as compared to the initial stage.

The heat-proof test is a process of maintaining the optical laminateand/or the optical functional layer at about 95° C. for about 750 hoursor so, or at about 105° C. for about 250 hours, as described above. Thisheat-proof test can be performed in a state where the upper surface andthe lower surface (upper whole surface and lower whole surface) of therelevant optical laminate and/or optical functional layer are in contactwith the glass substrate (soda lime glass plate having a thickness of1.1 mm or so). The contact may be a direct contact. This a* value changeamount can be measured in the manner described in the examples herein.

When the reddening occurs in the optical laminate and/or the opticalfunctional layer, a phenomenon, in which the transmittance is usuallylowered, appears. Since the optical laminate of the present applicationhas excellent resistance to the reddening, the change in transmittanceis also absent or minimized.

For example, in the same heat-proof test as for confirming Equation 1,for the optical laminate or the optical functional layer, the absolutevalue of the change amount (ΔTs) in the transmittance according toEquation 2 below (single transmittance when the optical laminate is apolarizing plate or the optical functional layer is a polarizing layer)may be within 5. The transmittance is the result measured for light inthe visible light region, for example, light in the range ofapproximately 380 nm to 780 nm using a JASCO V-7100 spectrophotometer.

ΔTs=T _(a) −T _(i)  [Equation 2]

In Equation 2, ΔTs is the change amount in the transmittance (singletransmittance when the optical laminate is a polarizing plate or theoptical functional layer is a polarizing layer), T_(a) is thetransmittance after the heat-proof test (single transmittance when theoptical laminate is a polarizing plate or the optical functional layeris a polarizing layer) (transmittance after the heat-proof endurancetest), and T_(i) is the transmittance before the heat-proof test (singletransmittance when the optical laminate is a polarizing plate or theoptical functional layer is a polarizing layer).

In another example, the absolute value of the change amount (ΔTs) may beabout 4.9 or less, about 4.8 or less, about 4.7 or less, about 4.6 orless, about 4.5 or less, about 4.4 or less, about 4.3 or less, about 4.2or less, about 4.1 or less, about 4 or less, about 3.9 or less, about3.8 or less, about 3.7 or less, about 3.6 or less, about 3.5 or less,about 3.4 or less, about 3.3 or less, about 3.2 or less, about 3.1 orless, about 3 or less, about 2.9 or less, about 2.8 or less, about 2.7or less, about 2.6 or less, about 2.5 or less, about 2.4 or less, about2.3 or less, about 2.2 or less, about 2.1 or less, about 1.9 or less,about 1.8 or less, about 1.7 or less, about 1.6 or less, about 1.5 orless, about 1.4 or less, about 1.3 or less, about 1.2 or less, about 1.1or less, about 1.0 or less, about 0.9 or less, about 0.8 or less, about0.7 or less, about 0.6 or less, about 0.5 or less, about 0.4 or less,about 0.3 or less, about 0.2 or less, or about 0.1 or less. The lowerthe change in the transmittance, the less the reddening, so that thelower limit of the absolute value of the change amount (ΔTs) is 0. Inanother example, the absolute value of such a change amount (ΔTs) mayalso be approximately more than 0.

The heat-proof test for measuring the transmittance change amount may beperformed under the same conditions as those of the heat-proof test formeasuring the a* value change amount. The transmittance can be measuredin the manner described in the examples herein.

The optical laminate comprises an optical functional layer. The termoptical functional layer is a layer that exhibits at least one opticallyintended function. An example of the optically intended function isgeneration of polarized light such as linearly polarized light orcircularly polarized light, reflection, refraction, absorption,scattering and/or phase retardation. In the optical field, variouslayers having such functions are known, where as an example of theoptical functional layer to be applied in the present application, allkinds of layers having a reddening problem among the known opticalfunctional layers may be included.

In one example, the optical functional layer may be a polarizing layeror a retardation layer. In this specification, the case where theoptical functional layer is a polarizing layer is described, but thekind of the optical functional layer is not limited to the polarizinglayer. In addition, when the optical functional layer is a polarizinglayer, the optical laminate may be a polarizing plate.

In this specification, the terms polarizing layer and polarizing platerefer to other objects. The term polarizing layer may refer to, forexample, a multilayer or a monolayer exhibiting a polarizing functionsolely, and the polarizing plate may refer to a laminate comprisingother elements having no polarizing function together with thepolarizing layer. Here, other elements included together with thepolarizing layer may be exemplified by a protective film or a protectivelayer of the polarizing layer, the reddening-resistant layer, aretardation layer, an adhesive layer, a pressure-sensitive adhesivelayer, a hard coating layer or a low reflection layer, and the like, butis not limited thereto.

Basically, the type of the polarizing layer applied in the presentapplication is not limited. A known most general polarizing layer is alinear absorbing polarizing layer, which is a so-called poly(vinylalcohol) (hereinafter, may be referred to as PVA) polarizing layer. Inthis specification, the term PVA means polyvinyl alcohol or a derivativethereof, unless otherwise specified. As the PVA polarizing layer, forexample, a stretched PVA film in which an anisotropic absorbent materialsuch as iodine or a dichroic dye is adsorbed and oriented, or aso-called coating PVA polarizing layer, which is formed thinly byapplying PVA to a coating method, and the like are known, but in thepresent application, all of the above-described polarizing layers may beapplied. In addition to the PVA polarizing layer, a polarizing plateformed of a liquid crystal compound such as LLC (lyotropic liquidcrystal), or a polarizing layer formed by aligning a polymerizableliquid crystal compound (so-called RM (reactive mesogen)) and a dichroicdye in a GH (guest-host) method, and the like may also be applied in thepresent application.

In the present application, in particular, even when an iodine-basedpolarizing layer is applied as the polarizing layer, the reddening ofthe iodine-based polarizing layer can be effectively prevented,alleviated, reduced, suppressed and/or delayed.

The iodine-based polarizing layer is a polarizing layer to which aniodine-based material is applied as the anisotropic absorbent material.Typically, as the anisotropic absorbent material, an iodine-basedmaterial may be applied, or a dichroic dye such as an azo dye may beapplied. The former case may be called an iodine-based polarizing layer,and the latter case may be called a dye-based polarizing layer. Ingeneral, the iodine-based polarizing layer may exhibit excellent opticalperformance (for example, high transmittance, high polarization degree,and high contrast) as compared to the dye-based polarizing layer.However, the iodine-based polarizing layer has significantly loweredheat resistance as compared with the dye-based polarizing layer. Inparticular, the iodine-based material included in the iodine-basedpolarizing layer is decomposed under high temperature and/or highhumidity conditions to easily generate I₂ materials, which causereddening through inappropriate absorption of the visible light region.Therefore, in applications where durability in high temperature and/orhigh humidity conditions is necessarily required, the dye-basedpolarizing layer is sometimes applied even if the loss of opticalcharacteristics is taken. However, according to the present application,even when the iodine-based polarizing layer is applied, furthermore,even when such an iodine-based polarizing layer is maintained and usedunder harsh conditions such as significantly high temperatureconditions, the reddening of the iodine-based polarizing layer can beeffectively prevented, alleviated, reduced, suppressed and/or delayed.Therefore, according to the present application, while the disadvantagesof the iodine-based polarizing layer are solved, the advantages can betaken.

The iodine-based polarizing layer may be an iodine-based PVA polarizinglayer. The iodine-based PVA polarizing layer is a polarizing layer inwhich an iodine-based material is oriented in the stretched PVA film orthe coating PVA polarizing layer.

According to the present application, even when the iodine-basedpolarizing layer having weak durability as above is applied, it ispossible to take the advantages of the polarizing layer whileeffectively preventing the reddening phenomenon, but the kind ofpolarizing layer applied in the present application is not limited tothe iodine-based polarizing layer.

The polarizing layer applied in the examples of the present applicationis an iodine-based PVA polarizing layer, and such a polarizing layer isusually produced by dyeing and stretching a PVA disc film. In theproduction process of the PVA polarizing layer, optionally, additionalprocesses such as swelling, crosslinking, washing and/or complementarycolor processes may also be performed, and a process of producing thePVA polarizing layer through such processes is well known.

In one example, as the polarizing layer, an iodine-based PVA polarizinglayer comprising a zinc component may be used, in order to securedurability, particularly, high temperature reliability of the opticallaminate. Here, the zinc component is exemplified by zinc and/or zincions, and the like. The PVA polarizing layer may also comprise apotassium component such as potassium or potassium ions as an additionalcomponent. If the polarizing layer containing such components is used,an optical laminate, in which durability is maintained stably even athigh temperature conditions, can be provided.

The ratio of the potassium and/or zinc component can be furtheradjusted. For example, in one example, the ratio (K/Zn) of the potassiumcomponent (K) and the zinc component (Zn) included in the PVA polarizinglayer may be in a range of 0.2 to 8. In another example, the ratio(K/Zn) may be about 0.4 or more, 0.6 or more, 0.8 or more, 1 or more,1.5 or more, 2 or more, or 2.5 or more, and may be 7.5 or less, 7 orless, 6.5 or less, 6 or less, 5.5 or less, about 5 or less, about 4.5 orless, or about 4 or less. The ratio may be a molar ratio or a weightratio.

The content of the potassium component included in the PVA polarizinglayer may be about 0.1 to 2 weight %. In another example, the ratio ofthe potassium component may be about 0.15 weight % or more, about 0.2weight % or more, about 0.25 weight % or more, about 0.3 weight % ormore, about 0.35 weight % or more, 0.4 weight % or more, or about 0.45weight % or more, about 0.5 weight % or more, about 0.55 weight % ormore, about 0.6 weight % or more, about 0.65 weight % or more, about 0.7weight % or more, about 0.75 weight % or more, or about 0.8 weight % ormore, and may be about 1.95 weight % or less, about 1.9 weight % orless, about 1.85 weight % or less, about 1.8 weight % or less, about1.75 weight % or less, about 1.7 weight % or less, about 1.65 weight %or less, about 1.6 weight % or less, about 1.55 weight % or less, about1.5 weight % or less, about 1.45 weight % or less, about 1.4 weight % orless, about 1.35 weight % or less, about 1.3 weight % or less, about1.25 weight % or less, about 1.2 weight % or less, about 1.15 weight %or less, about 1.1 weight % or less, about 1.05 weight % or less, about1 weight % or less, about 0.95 weight % or less, about 0.9 weight % orless, or about 0.85 weight % or less or so.

In one example, the ratio of the potassium component and the zinccomponent may be included to satisfy Equation 3 below.

0.70 to 1=1/(1+0.025d/R)  [Equation 3]

In Equation 3, d is the thickness (μm) of the PVA polarizing layer, andR is the ratio (K/Zn) of the weight ratio (K, unit: weight %) of thepotassium component and the weight ratio (Zn, unit: weight %) of thezinc component contained in the polarizing layer.

By comprising potassium and zinc components in the polarizing layer, apolarizing layer having excellent reliability at high temperature can beprovided.

In another example, the value of 1/(1+0.025d/R) in Equation 3 may alsobe about 0.75 or more, 0.8 or more, or 0.85 or more, and the value of1/(1+0.025d/R) may also be about 0.97 or less, about 0.95 or less, orabout 0.93 or less or so.

In the above-described details, the content of potassium and/or zinccomponents may be measured in the manner described in the examplesherein.

The polarizing layer applied in examples of the present application maybe a polarizing layer produced according to a known method for producinga polarizing layer. In addition, in the present application, when thepolarizing layer comprising the potassium and/or zinc component isintended to be applied as the polarizing layer, it may be produced bycontrolling process conditions in the known process for producing apolarizing layer such that zinc and/or potassium may be included in thepolarizing layer.

As described above, the PVA polarizing layer is usually produced bydyeing and stretching a PVA film (disc film), where optionally,swelling, crosslinking, washing and/or complementary color processes maybe further performed in the production process of the PVA polarizinglayer. The stretching process may be performed in a separate process, ormay also be performed simultaneously with other processes such asdyeing, swelling and/or crosslinking. In such a production process, atreatment solution such as a dyeing solution, a crosslinking solution, aswelling solution, a washing solution and/or a complementary colorsolution is applied, where by controlling the components of thistreatment solution, it may be determined whether the potassium and/orzinc components are included, or the ratio and the like may be adjusted.

In the dyeing process, the anisotropic absorbent material may beadsorbed and/or oriented to the PVA film. Such a dyeing process may beperformed together with the stretching process, if necessary. The dyeingmay be performed by immersing the film in a solution containing ananisotropic absorbent material, for example, an iodine solution. As theiodine solution, an aqueous solution or the like containing iodide ionsby iodine (I₂) and a iodinated compound which is a solubilizing agentmay be used. As the iodinated compound, for example, potassium iodide,lithium iodide, sodium iodide, zinc iodide, aluminum iodide, leadiodide, copper iodide, barium iodide, calcium iodide, tin iodide ortitanium iodide, and the like may be used. The concentration of iodineand/or iodide ions in the iodine solution may be adjusted inconsideration of the desired optical characteristics of the polarizinglayer, and such an adjustment manner is known. Typically, the content ofiodine in the dyeing solution (iodine solution) may be about 0.01 to 5weight % or so, and the concentration of the iodinated compound may beabout 0.01 to 10 weight % or so. In another example, the iodine contentmay be 0.05 weight % or more, 0.1 weight % or more, or 0.15 weight % ormore, and may also be 4.5 weight % or less, 4 weight % or less, 3.5weight % or less, 3 weight % or less, 2.5 weight % or less, 2 weight %or less, 1.5 weight % or less, 1 weight % or less, or 0.5 weight % orless or so. In another example, the concentration of the iodinatedcompound may be 0.05 weight % or more, 0.1 weight % or more, 0.5 weight% or more, 1 weight % or more, 1.5 weight % or more, or 2 weight % ormore, and may also be 9 weight % or less, 8 weight % or less, 7 weight %or less, 6 weight % or less, 5 weight % or less, 4 weight % or less, or3 weight % or less or so. In the dyeing process, the temperature of theiodine solution is usually about 20° C. to 50° C. or 25° C. to 40° C. orso, and the immersion time is usually about 10 seconds to 300 seconds or20 seconds to 240 seconds or so, without being limited thereto.

Although the stretching process is generally performed by uniaxialstretching, other types of stretching such as biaxial stretching mayalso be applied, if necessary. This stretching may also be performedtogether with the dyeing process and/or the crosslinking process to bedescribed below. The stretching method is not particularly limited and,for example, a wet method may be applied. For example, in this wetmethod, it is common to perform stretching after dyeing. The stretchingmay be performed together with crosslinking, and may also be performedmultiple times or in multiple stages. The above-described iodinatedcompound can be contained in the treatment solution applied to the wetstretching method. The concentration of the iodinated compound in thetreatment solution may be about 0.01 to 10 weight % or so. In anotherexample, the concentration of the iodinated compound may be 0.05 weight% or more, 0.1 weight % or more, 0.5 weight % or more, 1 weight % ormore, 1.5 weight % or more, or 2 weight % or more, and may also be 9weight % or less, 8 weight % or less, 7 weight % or less, 6 weight % orless, 5 weight % or less, 4 weight % or less, or 3.5 weight % or less orso. In the stretching, the treatment temperature is usually in a rangeof 25° C. or more, 30° C. to 85° C. or 40° C. to 70° C. or so, and thetreatment time is usually 10 seconds to 800 seconds or 30 seconds to 500seconds, without being limited thereto. In the stretching process, thetotal draw ratio may be adjusted in consideration of the orientationcharacteristics and the like, where the total draw ratio may be 3 to 10times, 4 to 8 times or 5 to 7 times based on the original length of thePVA film, but is not limited thereto. Here, when the stretching is alsoinvolved in other processes, such as swelling, dyeing and/orcrosslinking processes, in addition to the stretching process, the totaldraw ratio may mean a cumulative draw ratio including the stretching inthe respective processes. Such a total draw ratio may be adjusted to anappropriate range in consideration of orientation, processability orstretching cutting possibility of the polarizing layer, and the like.

In the production process of the polarizing layer, the swelling processmay be performed in addition to the dyeing and stretching, which isnormally performed before the dyeing process. Contamination or anantiblocking agent on the PVA film surface can be washed by theswelling, whereby there is also an effect capable of reducing unevennesssuch as dyeing deviation.

In the swelling process, water, distilled water or pure water, and thelike can be usually used. The main component of the relevant treatmentliquid is water, and if necessary, a small amount of an iodinatedcompound such as potassium iodide or an additive such as a surfactant,or alcohol, and the like can be included therein. The treatmenttemperature in the swelling process is usually 20° C. to 45° C. or so,or 20° C. to 40° C. or so, but is not limited thereto. Since theswelling deviations can cause dyeing deviations, the process variablescan be adjusted so that the occurrence of such swelling deviations issuppressed as much as possible. Optionally, the proper stretching mayalso be performed in the swelling process. The draw ratio may be 6.5times or less, 1.2 to 6.5 times, 2 times to 4 times, or 2 times to 3times, based on the original length of the PVA-based film. Thestretching in the swelling process can control the stretching in thestretching process performed after the swelling process to be small andcan control so that the stretching failure of the film does not occur.

The cross-linking process can be performed, for example, using across-linking agent such as a boron compound. The order of thecross-linking process is not particularly limited, and the process canbe performed, for example, with the dyeing and/or stretching processes,or can proceed separately. The cross-linking process may also beperformed several times. As the boron compound, boric acid or borax maybe used. The boron compound can be generally used in the form of anaqueous solution or a mixed solution of water and an organic solvent,and usually an aqueous solution of boric acid is used. The boric acidconcentration in the boric acid aqueous solution can be selected in anappropriate range in consideration of the cross-linking degree and theheat resistance thereof. An iodinated compound such as potassium iodidecan be contained in an aqueous solution of boric acid or the like. Theconcentration of the iodinated compound in the boric acid aqueoussolution may be about 0.01 to 10 weight % or so. In another example, theconcentration of the iodinated compound may be 0.05 weight % or more,0.1 weight % or more, 0.5 weight % or more, 1 weight % or more, 1.5weight % or more, or 2 weight % or more, and may also be 9 weight % orless, 8 weight % or less, 7 weight % or less, 6 weight % or less, 5weight % or less, 4 weight % or less, or 3.5 weight % or less or so. Thecrosslinking process may be performed by immersing the PVA film in aboric acid aqueous solution or the like, and in this process, thetreatment temperature is usually in a range of 25° C. or more, 30° C. to85° C. or 30° C. to 60° C., and the treatment time is usually about 5seconds to 800 seconds or about 8 seconds to 500 seconds or so.

In the production process of the polarizing layer, a metal ion treatmentmay be performed, which may be generally referred to as a complementarycolor process. Such a treatment is performed, for example, by immersinga PVA film in an aqueous solution containing a metal salt. Through this,the metal component such as metal ions can be contained in thepolarizing layer, and in this process, the type or ratio of the metalcomponent may be adjusted. As the metal ion that can be applied, metalions of transition metals such as cobalt, nickel, zinc, chromium,aluminum, copper, manganese or iron can be exemplified, and the colortone can also be adjusted by selecting a proper kind among them.

In order to produce a polarizing layer containing zinc, a zinc componentmay be included in a treatment liquid (aqueous solution containing ametal salt) applied in the complementary color process. However, ifnecessary, the zinc component may also be applied during otherprocesses, where the zinc component may also be included in anothertreatment liquid such as a dyeing solution or a crosslinking solution,or a separate treatment liquid. The zinc component may be introduced bydissolving one or more zinc salts selected from, for example, zincchloride, zinc iodide, zinc sulfate, zinc nitrate, zinc acetate and thelike in the aqueous solution. In this case, the concentration of thezinc salt may be adjusted to about 0.01 to 10 weight % or so in order toachieve the desired zinc content. In another example, the concentrationof the zinc salt may be 0.05 weight % or more, 0.1 weight % or more, 0.5weight % or more, 1 weight % or more, 1.5 weight % or more, or 2 weight% or more, or may also be 9 weight % or less, 8 weight % or less, 7weight % or less, 6 weight % or less, 5 weight % or less, 4 weight % orless, or 3 weight % or less or so. If necessary, a potassium componentmay also be included in the treatment liquid. The potassium componentmay be exemplified by a potassium salt such as potassium iodide. Theconcentration of the potassium salt may be about 0.01 to 10 weight % orso. In another example, the concentration may also be 0.05 weight % ormore, 0.1 weight % or more, 0.5 weight % or more, 1 weight % or more,1.5 weight % or more, 2 weight % or more, 2.5 weight % or more, 3 weight% or more, 3.5 weight % or more, 4 weight % or more, 4.5 weight % ormore, or 5 weight % or more, or may also be 9 weight % or less, 8 weight% or less, 7 weight % or less, or 6 weight % or less or so. By applyingthe zinc salt or potassium salt as above in the complementary colorprocess, the desired level of zinc and potassium components can beincluded in the polarizing layer.

In the production process of the polarizing layer, a washing process maybe performed after dyeing, crosslinking and stretching. Usually, thiswashing process may be performed before the complementary color process,which may be performed with water. If necessary, in the water applied tothe washing process, other components such as iodine, iodide, othermetal salts, or a liquid alcohol such as methanol, ethanol, isopropylalcohol, butanol or propanol may also be blended in an appropriateamount.

After such processes, a drying process may be performed to produce apolarizing layer. For example, in consideration of the moisture contentrequired for the polarizing layer and the like, the drying process maybe performed at an appropriate temperature for a suitable time, and suchconditions are not particularly limited.

As described above, in the above process, the zinc and/or potassiumcomponent may be included in the polarizing layer. However, the mannerfor producing the polarizing layer comprising the zinc and/or potassiumcomponent is not limited to the above. For example, the zinc salt isincluded in the treatment liquid applied to the swelling, dyeing,crosslinking, stretching and/or washing treatment, whereby in anotherprocess other than the complementary color process, the zinc componentmay also be included in the polarizing layer. In addition, since thepotassium component, such as potassium iodide, may also be contained inthe treatment liquid applied to the swelling, dyeing, crosslinking,stretching and/or washing treatment, and the like, the ratio of thepotassium component may also be adjusted in this process. While thoseskilled in the art appropriately adopt a general method for producing apolarizing layer, the desired level of zinc and/or potassium componentsmay be included in the polarizing layer depending on the purpose.

The thickness of the polarizing layer is not limited. In the presentapplication, since a generally known polarizing layer may be applied,the applied thickness is also a usual thickness. Usually, the thicknessof the polarizing layer may be in a range of 5 μm to 80 μm, but is notlimited thereto.

The optical laminate of this application comprises thereddening-resistant layer.

The present application relates to an optical laminate or display devicecomprising the reddening-resistant layer, or to the reddening-resistantlayer.

The term reddening-resistant layer is a layer capable of preventing,alleviating, reducing, suppressing and/or delaying the reddening of theoptical laminate and/or optical functional layer, as mentioned above.The reddening of the optical laminate and/or optical functional layer isexpected to be caused by heat and/or moisture, or at least acceleratedby heat and/or moisture. As the applications of display devices expand,the optical laminate and/or the optical functional layer are moreexposed to higher temperatures, whereby the optical functional layer orthe optical laminate, in which the reddening has not been a problemformerly, frequently causes the reddening in the new applications.

Accordingly, a layer, which plays a role in blocking heat applied to theoptical laminate and/or the optical functional layer, reducing thedegree of the applied heat or slowing down the heat transfer rate, maybe applied as the reddening-resistant layer.

In one example, the reddening-resistant layer is a void-containing layer(porous layer) to be described below, or a laminate comprising thevoid-containing layer (porous layer), which may be a layer presentsufficiently adjacent to the optical functional layer. By making thereddening-resistant layer into a void-containing layer (porous layer) ora layer comprising the void-containing layer (porous layer), heattransfer can be effectively blocked. Here, the optical functional layermay be a layer which causes reddening, like the aforementionediodine-based polarizing layer. In addition, the presence of thereddening-resistant layer sufficiently adjacent to the opticalfunctional layer means a case where the position of thereddening-resistant layer and the distance between thereddening-resistant layer and the optical functional layer is adjustedso that the reddening-resistant layer can block the heat transfer to theoptical functional layer in a level capable of preventing, alleviating,reducing, suppressing and/or delaying the reddening. For example, evenif a layer having a configuration similar to that of thereddening-resistant layer of the present application, which is describedbelow, exists, such a layer cannot be said to be the reddening-resistantlayer mentioned in the present application, unless such a layer ispresent at the position and the distance that can block the heattransfer to the optical functional layer. For example, the sufficientlyadjacent presence may mean a case that the distance between the opticalfunctional layer, which causes the reddening, and thereddening-resistant layer is within about 90 μm, within about 85 μm,within about 80 μm, within about 75 μm, within about 70 μm, within about65 μm, within about 60 μm, within about 55 μm, within about 50 μm,within about 45 μm, within about 40 μm, within about 35 μm, within about30 μm, within about 25 μm, within about 20 μm, within about 15 μm,within about 10 μm, within about 5 μm, within about 1 μm, within about0.9 μm, within about 0.8 μm, within about 0.7 μm, within about 0.6 μm,within about 0.5 μm, within about 0.4 μm, within about 0.3 μm, or withinabout 0.2 μm. In addition, the sufficient adjacency also includes thecase where the optical functional layer and the reddening-resistantlayer contact each other, where the distance is 0 μm. Therefore, thelower limit of the distance is 0 μm. In another example, the distancemay also be about 0.01 μm or more, about 0.02 μm or more, about 0.03 μmor more, about 0.04 μm or more, about 0.05 μm or more, about 0.09 μm ormore, or about 0.1 μm or more or so. Here, the distance may be theshortest interval, the maximum interval or the average interval betweenthe facing surfaces of the reddening-resistant layer and the opticalfunctional layer.

In one example, the reddening-resistant layer is a void-containing layer(porous layer) to be described below, or a laminate comprising thevoid-containing layer (porous layer), which may be a layer having asufficient thickness capable of preventing the reddening of the opticalfunctional layer. That is, even when the reddening-resistant layer ismade into a void-containing layer (porous layer) or a layer comprisingthe void-containing layer (porous layer), heat transfer cannot beeffectively blocked unless a suitable thickness is secured. For example,even if a layer having a configuration similar to that of thereddening-resistant layer of the present application, which is describedbelow, exists, such a layer cannot be said to be the reddening-resistantlayer mentioned in the present application unless such a layer has athickness that can block the heat transfer to the optical functionallayer. In one example, the sufficient thickness may also be, forexample, about 200 nm or more, about 250 nm or more, about 300 nm ormore, about 350 nm or more, about 400 nm or more, about 450 nm or more,about 500 nm or more, about 550 nm or more, about 600 nm or more, about650 nm or more, about 700 nm or more, about 750 nm or more, about 800 nmor more, about 850 nm or more, or about 900 nm or more or so. The upperlimit of the thickness is not particularly limited. The thicker thereddening-resistant layer is, the better the effect of preventing,alleviating, reducing, suppressing and/or delaying heat is improved.Therefore, the upper limit of the thickness of the reddening-resistantlayer or the void-containing layer (porous layer) may be selected inconsideration of the thickness required for the optical laminate, andthe like as long as the effect of preventing, alleviating, reducing,suppressing and/or delaying heat is ensured, without any speciallimitation. In one example, the thickness of the reddening-resistantlayer or the void-containing layer (porous layer) may also be about3,000 nm or less, about 2,900 nm or less, about 2,800 nm or less, about2,700 nm or less, about 2,600 nm or less, about 2,500 nm or less, about2,400 nm or less, about 2,300 nm or less, about 2,200 nm or less, about2,100 nm or less, about 2,000 nm or less, or about 1,950 nm or less orso.

In one example, the reddening-resistant layer may be a layer having athermal diffusivity in a predetermined range. For example, thereddening-resistant layer may have a thermal diffusivity in a level thatafter forming the relevant reddening-resistant layer on a polymer filmto produce a laminate, the thermal diffusivity measured at 95° C. withrespect to the laminate is 90% or less relative to the thermaldiffusivity of the polymer film alone.

In this case, the reddening-resistant layer may satisfy the followingequation 4.

In the present application, the term reddening-resistant layer may referto a void-containing layer (porous layer) itself or a laminatecomprising at least the void-containing layer (porous layer). Therefore,the reddening-resistant layer referred to in the following equation 4may be a void-containing layer (porous layer) or a laminate comprisingthe same.

H _(L)≤0.9×H _(P)  [Equation 4]

In Equation 4, H_(L) is a thermal diffusivity of a laminate of a polymerfilm and the reddening-resistant layer formed on one side of the polymerfilm, and H_(P) is the thermal diffusivity of the polymer film.

In this specification, the type of the polymer film for measuring thethermal diffusivity is not particularly limited. For example, thepolymer film in Equation 4 above may be a TAC (triacetyl cellulose) filmhaving a thickness of about 60 μm. In another example, the thermaldiffusivity (95° C.) of the laminate may be about 89% or less or so,about 88% or less or so, about 87% or less or so, about 86% or less orso, about 85% or less or so, about 84% or less or so, about 83% or lessor so, about 82% or less or so, about 81% or less or so, about 80% orless or so, about 79% or less or so, about 78% or less or so, about 77%or less or so, about 76% or less or so, about 75% or less or so, about74% or less or so, about 73% or less or so, about 72% or less or so,about 71% or less or so, about 70% or less or so, about 69% or less orso, about 68% or less or so, about 67% or less or so, about 66% or lessor so, or about 65% or less or so, or may also be about 10% or more orso, about 11% or more or so, about 12% or more or so, about 13% or moreor so, about 14% or more or so, about 15% or more or so, about 16% ormore or so, about 17% or more or so, about 18% or more or so, about 19%or more or so, about 20% or more or so, about 21% or more or so, about22% or more or so, about 23% or more or so, about 24% or more or so,about 25% or more or so, about 26% or more or so, about 27% or more orso, about 28% or more or so, about 29% or more or so, about 30% or moreor so, about 31% or more or so, about 32% or more or so, about 33% ormore or so, about 34% or more or so, about 35% or more or so, about 36%or more or so, about 37% or more or so, about 38% or more or so, about39% or more or so, about 40% or more or so, about 41% or more or so,about 42% or more or so, about 43% or more or so, about 44% or more orso, about 45% or more or so, about 46% or more or so, about 47% or moreor so, about 48% or more or so, about 49% or more or so, about 50% ormore or so, about 51% or more or so, about 52% or more or so, about 53%or more or so, about 54% or more or so, about 55% or more or so, about56% or more or so, about 57% or more or so, about 58% or more or so,about 59% or more or so, or about 60% or more or so, of the thermaldiffusivity (95° C.) (H_(P)) of the TAC film.

Therefore, the coefficient multiplied by H_(P) in Equation 4 may be0.89, 0.88, 0.87, 0.86, 0.85, 0.84, 0.83, 0.82, 0.81, 0.80, 0.79, 0.78,0.77, 0.76, 0.75, 0.74, 0.73, 0.72, 0.71, 0.70, 0.69, 0.68, 0.67, 0.66or 0.65. In Equation 4, H_(L) may also be about 0.10×H_(P) or more,about 0.11×H_(P) or more, about 0.12×H_(P) or more, about 0.13×H_(P) ormore, about 0.14×H_(P) or more, about 0.15×H_(P) or more, about0.16×H_(P) or more, about 0.17×H_(P) or more, about 0.18×H_(P) or more,about 0.19×H_(P) or more, about 0.20×H_(P) or more, about 0.21×H_(P) ormore, about 0.22×H_(P) or more, about 0.23×H_(P) or more, about0.24×H_(P) or more, about 0.25×H_(P) or more, about 0.26×H_(P) or more,about 0.27×H_(P) or more, about 0.28×H_(P) or more, about 0.29×H_(P) ormore, about 0.30×H_(P) or more, about 0.31×H_(P) or more, about0.32×H_(P) or more, about 0.33×H_(P) or more, about 0.34×H_(P) or more,about 0.35×H_(P) or more, about 0.36×H_(P) or more, about 0.37×H_(P) ormore, about 0.38×H_(P) or more, about 0.39×H_(P) or more, about0.40×H_(P) or more, about 0.41×H_(P) or more, about 0.42×H_(P) or more,about 0.43×H_(P) or more, about 0.44×H_(P) or more, about 0.45×H_(P) ormore, about 0.46×H_(P) or more, about 0.47×H_(P) or more, about0.48×H_(P) or more, about 0.49×H_(P) or more, about 0.50×H_(P) or more,about 0.51×H_(P) or more, about 0.52×H_(P) or more, about 0.53×H_(P) ormore, about 0.54×H_(P) or more, about 0.55×H_(P) or more, about0.56×H_(P) or more, about 0.57×H_(P) or more, about 0.58×H_(P) or more,about 0.59×H_(P) or more, or about 0.60×H_(P) or more.

Surface characteristics of the reddening-resistant layer or thevoid-containing layer (porous layer) may be controlled. In order to bepositioned adjacent to an optical functional layer that the reddeningshould be prevented, alleviated, reduced, suppressed and/or delayed, thereddening-resistant layer or the void-containing layer (porous layer)may be directly attached to the optical functional layer, or may beattached to another layer of the optical laminate adjacent to theoptical functional layer. In this case, by controlling the surfacecharacteristics of the reddening-resistant layer or the void-containinglayer (porous layer), the relevant reddening-resistant layer orvoid-containing layer (porous layer) may be attached to the opticalfunctional layer or another layer while having excellent adhesivenesstherewith, thereby more effectively preventing, alleviating, reducing,suppressing and/or delaying the reddening. For example, thereddening-resistant layer or the void-containing layer (porous layer)may include at least one surface having a surface area ratio of about0.02 or more as measured by an atomic force microscope (AFM). Forexample, at least one of the main surfaces of the reddening-resistantlayer or the void-containing layer (porous layer), or both surfaces mayhave the above surface area ratio. In one example, the surface of thereddening-resistant layer or void-containing layer (porous layer) havingat least the surface area ratio may be a surface facing the opticalfunctional layer or another layer to which the reddening-resistant layeror the void-containing layer (porous layer) is attached. In anotherexample, the surface area ratio of the reddening-resistant layer or thevoid-containing layer (porous layer) may be about 0.022 or more, about0.024 or more, about 0.026 or more, about 0.028 or more, about 0.03 ormore, about 0.032 or more, or about 0.034 or more, or may also be about0.5 or less, about 0.45 or less, about 0.4 or less, about 0.35 or less,about 0.3 or less, or about 0.25 or less or so. The surface area ratiocan be measured by the method as described in the examples.

The reddening-resistant layer or the void-containing layer (porouslayer) may exhibit a desired level of reflectance for infrared rays.Since heat is also transferred in the form of infrared rays, it ispossible to secure desired anti-reddening characteristics even when theappropriate reflectance is shown therefor. In this specification, theterm infrared rays may mean electromagnetic waves having any onewavelength in a range of approximately 800 nm to 1,300 nm, orwavelengths within a range of some region in the range or wavelengths ofthe entire region. Accordingly, the infrared reflectance may bereflectance for any one wavelength in the range of 800 nm to 1,300 nm,or may be average reflectance for the range of some region in the rangeor the entire region. The reflectance may be measured according to themanner described in the examples herein. The reddening-resistant layeror the void-containing layer (porous layer) may have the infraredreflectance of about 2% or more. In another example, the reflectance maybe about 2.5% or more, about 3% or more, about 3.5% or more, or about 4%or more. Since it means that the higher the value of the reflectance,the reddening-resistant layer or the void-containing layer (porouslayer) can appropriately block and/or delay the heat applied to theoptical laminate and/or the optical functional layer, the upper limit isnot particularly limited. Exemplarily, the infrared reflectance may alsobe about 10% or less, about 9% or less, about 8% or less, about 7% orless, about 6% or less, or about 5% or less or so.

As the reddening-resistant layer or the void-containing layer (porouslayer), various layers may be applied without particular limitation, aslong as they have suitable transmittance that can be applied to theoptical laminate and have the above characteristics (thermaldiffusivity, surface area ratio and/or reflectance). If they have theabove characteristics, it is possible to prevent, alleviate, reduce,suppress and/or delay the reddening, so that as long as thetransmittance is properly secured, all can be theoretically applied inthe present application. Here, the transmittance required in the opticallaminate may be about 70% or more, about 75% or more, about 80% or more,about 85% or more, or about 90% or more. The higher the value of thetransmittance is, the more suitable it is, so that the upper limitthereof is not particularly limited. For example, the transmittance maybe about 100% or less, about 95% or less, or about 90% or less or so.Here, the transmittance may be transmittance or average transmittancefor light in a visible light region, for example, any one wavelength ina range of approximately 380 nm to 780 nm, or wavelengths in apredetermined region in the range or the entire region. When applying avoid-containing layer (porous layer) or a laminate comprising thevoid-containing layer (porous layer) as the reddening-resistant layer,heat transfer can be effectively blocked by the voids present in thereddening-resistant layer, but it can be disadvantageous in terms oftransmittance as the voids scatter or diffract light in the opticallaminate. However, in the present application, by controlling the shapeof the voids, as described below, there is no drop in transmittance dueto scattering or diffraction of the light, or such a drop can be limitedat least to a level that there is no problem in use.

As the reddening-resistant layer, for example, a void-containing layer(porous layer) or a layer comprising the void-containing layer (porouslayer) can be applied. That is, as described above, in the presentapplication, the reddening-resistant layer may refer to thevoid-containing layer (porous layer) itself, or may also refer to thelaminate comprising the void-containing layer (porous layer) and otherlayers as long as it satisfies the purpose of preventing the reddening.In one example, the reddening-resistant layer may exhibit theaforementioned characteristics (thermal diffusivity, surface area ratioand/or infrared reflectance) by comprising the void-containing layer(porous layer). Thus, the above-mentioned thermal diffusivity, surfacearea ratio and/or infrared reflectance may be for the void-containinglayer (porous layer), or may also be for the laminate comprising atleast the void-containing layer (porous layer). Here, the type of otherelements included in the reddening-resistant layer together with thevoid-containing layer (porous layer) is not particularly limited, whichmay be, for example, elements constituting the optical laminate such asthe polarizing layer or its protective film and the retardation film.

The void-containing layer is a layer comprising at least one or morevoids therein, where the reddening-resistant layer can perform thefunction of preventing, alleviating, reducing, suppressing and/ordelaying heat transfer through these voids. In the present application,when the void-containing layer is referred to as a porous layer, atleast two or more voids are included inside the void-containing layer.In order to secure the above-described physical properties, for example,thermal diffusivity, surface area ratio and/or reflectance, and thelike, it is important that the reddening-resistant layer comprises thevoid-containing layer (porous layer). At this time, the shape of thevoids included in the void-containing layer (porous layer) is notparticularly limited, which may be substantially spherical orellipsoidal, or other various types of voids may be all applied.

The size (diameter) of the voids may be in a range of approximately 0.5nm to 100 nm. When the relevant void is spherical, the size of the voidmeans the particle diameter, and when the void is not spherical, thevoid has been assumed to have the same volume sphere and it is theparticle diameter of the sphere at that time. In another example, thesize of the void may be about 1 nm or more, about 2 nm or more, about 3nm or more, about 4 nm or more, about 5 nm or more, about 6 nm or more,about 7 nm or more, about 8 nm or more, about 9 nm or more, about 10 nmor more, about 11 nm or more, about 12 nm or more, about 13 nm or more,about 14 nm or more, about 15 nm or more, about 16 nm or more, about 17nm or more, about 18 nm or more, about 19 nm or more, about 20 nm ormore, about 21 nm or more, about 22 nm or more, about 23 nm or more,about 24 nm or more, about 25 nm or more, about 26 nm or more, about 27nm or more, about 28 nm or more, about 29 nm or more, about 31 nm ormore, about 32 nm or more, about 33 nm or more, about 34 nm or more,about 35 nm or more, about 36 nm or more, about 37 nm or more, or about38 nm or more, or may also be about 99 nm or less, 98 nm or less, about97 nm or less, about 96 nm or less, about 95 nm or less, about 94 nm orless, about 93 nm or less, about 92 nm or less, about 91 nm or less,about 90 nm or less, about 89 nm or less, about 88 nm or less, about 87nm or less, about 86 nm or less, about 85 nm or less, about 84 nm orless, about 83 nm or less, about 82 nm or less, about 81 nm or less,about 79 nm or less, about 78 nm or less, about 77 nm or less, about 76nm or less, about 75 nm or less, about 74 nm or less, about 73 nm orless, about 72 nm or less, about 71 nm or less, about 69 nm or less,about 68 nm or less, about 67 nm or less, about 66 nm or less, about 65nm or less, about 64 nm or less, about 63 nm or less, about 62 nm orless, about 61 nm or less, about 59 nm or less, about 58 nm or less,about 57 nm or less, about 56 nm or less, about 55 nm or less, about 54nm or less, about 53 nm or less, about 52 nm or less, about 51 nm orless, about 50 nm or less, about 49 nm or less, about 48 nm or less,about 47 nm or less, about 46 nm or less, or about 45 nm or less or so.

In order to maximize the effect of the reddening-resistant layer, tosecure the aforementioned physical properties (thermal diffusivity,surface area ratio and/or reflectance, etc.), and to maintain thetransmittance, the position or distribution of the voids in thevoid-containing layer (porous layer) can be controlled.

For example, the reddening-resistant layer or the void-containing layer(porous layer) may exhibit at least one peak within a scattering vectorrange of 0.06 nm⁻¹ to 0.209 nm⁻¹ in a log value graph of scatteringintensity of a small angle X-ray scattering (SAXS) analysis. Thecharacteristic is a characteristic which reflects the average distancebetween voids. For example, the fact that the scattering vectorexhibiting the peak becomes smaller means a tendency that the averagedistance between the voids in the reddening-resistant layer or thevoid-containing layer (porous layer) becomes farther, and conversely,the fact that it becomes larger means a tendency that the averagedistance between the voids becomes closer.

When the scattering vector is about 0.06 nm⁻¹ or more, it isadvantageous in the characteristic that as the voids are appropriatelydensified in the reddening-resistant layer or the void-containing layer(porous layer), the applied heat can be blocked or reduced. Also, whenthe vector is about 0.209 nm⁻¹ or less, the voids are arranged atappropriate intervals in the reddening-resistant layer or thevoid-containing layer (porous layer), so that the surface roughness ofthe reddening-resistant layer or the void-containing layer (porouslayer), or the like, is maintained at an appropriate level, which canmake the application of the reddening-resistant layer or thevoid-containing layer (porous layer) to the optical laminate easier. Inaddition, the transmittance of the reddening-resistant layer can also bemaintained in the appropriate range within the scattering vector range.In another example, the scattering vector from which the peak isidentified may be about 0.065 nm⁻¹ or more, about 0.07 nm⁻¹ or more,about 0.075 nm⁻¹ or more, about 0.08 nm⁻¹ or more, about 0.085 nm⁻¹ ormore, about 0.09 nm⁻¹ or more, about 0.095 nm⁻¹ or more, or 0.1 nm⁻¹ ormore, and may also be about 0.205 nm⁻¹ or less, about 0.2 nm⁻¹ or less,about 0.19 nm⁻¹ or less, about 0.185 nm⁻¹ or less, about 0.18 nm⁻¹ orless, or about 0.16 nm⁻¹ or less.

Here, the peak is the extreme value or inflection point that in the logvalue graph of the scattering intensity identified by the analysis, thelog value of the scattering intensity is convex upward. The scatteringvector is a value defined by Equation 5 below, where at least one ormore peaks may be identified within a range of such a scattering vector.

q=4π sin(θ/λ)  [Equation 5]

In Equation 5, q is the scattering vector, θ is the value ½ times thescattering angle, and 2 is the wavelength (unit: nm) of the irradiatedX-ray.

The manner of performing the small angle X-ray scattering evaluation isin accordance with the description of the examples herein.

The reddening-resistant layer or the void-containing layer (porouslayer) may have an A value of 1.5 or less, a B value in a range of 0 to0.01 and a C value in a range of 0 to 0.001, which satisfy the followingequation 6.

$\begin{matrix}{{n(\lambda)} = {A + \frac{B}{\lambda^{2}} + \frac{C}{\lambda^{4}}}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

In Equation 6, n(λ) is the refractive index of the reddening-resistantlayer or the void-containing layer (porous layer) at a wavelength of λ,and λ is any one wavelength in a range of 300 to 1800 nm.

Equation 6 fits the ellipticity of polarization measured by theellipsometry of the reddening-resistant layer or the void-containinglayer (porous layer) according to a so-called Cauchy model. When thereddening-resistant layer or the void-containing layer (porous layer)has A, B and C values in the above-described ranges satisfying Equation6 above, the reddening-resistant layer or the void-containing layer(porous layer) may have void characteristics that can express thereddening function. Equation 6 above reflects the refractive indexcharacteristic of the reddening-resistant layer or the void-containinglayer (porous layer). The total refractive index of thereddening-resistant layer or the void-containing layer (porous layer) isdetermined by the refractive index of the voids constituting thereddening-resistant layer or the void-containing layer (porous layer),and the refractive index of other components, such as a binder, otherthan the voids. Therefore, the A, B and C values of thereddening-resistant layer or the void-containing layer (porous layer) inEquation 6 above may reflect the quantity of voids in thereddening-resistant layer. In one example, when the A, B and/or C valuesare within the above ranges, the surface roughness of thereddening-resistant layer or the void-containing layer (porous layer),or the like, is maintained in an appropriate level, while the voids inthe reddening-resistant layer or the void-containing layer (porouslayer) are present in a level capable of appropriately blocking ordelaying the movement of heat, so that the application of thereddening-resistant layer or the void-containing layer (porous layer) tothe optical laminate can be more easily performed. Furthermore, in theranges of the A, B and/or C values, the transmittance of thereddening-resistant layer or the void-containing layer (porous layer) inthe optical laminate can also be maintained stably.

In another example, the A value may be about 1.1 or more, about 1.15 ormore, about 1.2 or more, about 1.25 or more, or about 1.3 or more. Here,in another example, the B value may be about 0.0001 or more, about0.0002 or more, about 0.0003 or more, about 0.0004 or more, about 0.0005or more, about 0.0006 or more, or about 0.0007 or more, or may also beabout 0.009 or less, about 0.008 or less, about 0.007 or less, about0.006 or less, about 0.005 or less, or about 0.004 or less or so. Here,in another example, the C value may be about 0.000001 or more, about0.000002 or more, about 0.000003 or more, about 0.000004 or more, about0.000005 or more, about 0.000006 or more, about 0.000007 or more, about0.000008 or more, about 0.000009 or more, about 0.00001 or more, about0.00002 or more, about 0.00003 or more, about 0.00004 or more, about0.00005 or more, about 0.00006 or about 0.00007 or more, or may also beabout 0.0009 or less, about 0.0008 or less, about 0.0007 or less, about0.0006 or less, about 0.0005 or less, or about 0.0004 or less or so.

In Equation 6, λ may be any one wavelength in the range of about 300 toabout 1800 nm, and in one example, it may be about 400 nm or more, orabout 500 nm or more, or may be about 1700 nm or less, about 1600 nm orless, about 1500 nm or less, about 1400 nm or less, about 1300 nm orless, about 1200 nm or less, about 1100 nm or less, about 1000 nm orless, about 900 nm or less, about 800 nm or less, about 700 nm or less,or about 600 nm or less, or may be a wavelength range of about 550 nm.The reddening-resistant layer or void-containing layer (porous layer)satisfying Equation 6 may have a refractive index (based on a wavelengthof 550 nm) of about 1.5 or less, and in another example, the refractiveindex may be about 1.1 or more, or about 1.15 or more.

The volume fraction of the voids in the reddening-resistant layer or thevoid-containing layer (porous layer) may be about 0.1 or more. When thetotal volume of the reddening-resistant layer or the void-containinglayer (porous layer) has been converted to one, the volume fraction isthe ratio of the space volume occupied by the voids. In this range, thereddening-resistant layer or the void-containing layer (porous layer)can appropriately block or reduce heat transfer. Also, in the range, thetransmittance of the reddening-resistant layer or the void-containinglayer (porous layer) in the optical laminate can also be maintainedstably. The volume fraction can be measured by confirming the density,mass, and volume of the reddening-resistant layer or the void-containinglayer (porous layer) through a buoyancy method or the like, or when thereddening-resistant layer or the void-containing layer (porous layer) isformed by using hollow particles, as described below, it can beconfirmed through the amount of the hollow particles and the amount ofthe binder as applied, and the like.

The reddening-resistant layer or the void-containing layer (porouslayer) may be formed in various ways. A representative method of forminga layer containing voids is a manner of applying hollow particles.Therefore, in one example, the reddening-resistant layer may comprise atleast a binder and hollow particles.

By controlling the refractive indexes of the binder and the shellportion of the hollow particles, the size distribution of the hollowparticles and the pores therein, the amount of the hollow particles, andthe like, the above-described characteristics (thermal diffusivity(Equation 4), surface characteristics (surface area ratio of AFM),infrared reflectance, visible light transmittance, SAXS characteristics,volume fraction and/or refractive index characteristics) can besatisfied.

Various kinds of binders may be applied without particular limitation.For example, as the binder, various curable resin compositionsapplicable for optics may be applied. The resin applicable for opticsincludes, for example, acrylic series, epoxy series and/or siliconeseries, and the like, where the binder may be formed by applying theresin or a precursor capable of forming the same. Such a resin orprecursor may be curable, which may be, for example, a material that iscured by irradiation of light such as ultraviolet rays or electronbeams, a material that is cured by heat, or a material that is cured byother actions such as moisture.

As the binder, those having a refractive index (based on a wavelength of550 nm) in a range of approximately 1.1 to 1.6 may be applied. Thereddening-resistant layer satisfying Equation 6 as described above maybe easily formed by combining it under this refractive index range withhollow particles. In another example, the refractive index may be about1.15 or more, about 1.2 or more, about 1.25 or more, about 1.3 or more,about 1.35 or more, or about 1.4 or more, or may be about 1.55 or less,or about 1.5 or less or so.

A typical binder that satisfies such a refractive index is an acrylicbinder. The binder of the reddening-resistant layer may comprise apolymerized unit of a polymerizable acrylic compound.

In one example, as the acrylic compound, alkyl (meth)acrylates or alkoxy(meth)acrylates having an alkyl group or alkoxy group with 1 to 20carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbonatoms or 1 to 4 carbon atoms; monofunctional acrylate compounds such as2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate or8-hydroxyoctyl (meth)acrylate; bifunctional acrylates such as1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate,neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate,neopentylglycol adipate di(meth)acrylate, hydroxypivalic acid neopentylglycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactonemodified dicyclopentenyl di(meth)acrylate, ethylene oxide modifieddi(meth)acrylate, di(meth)acryloxyethyl isocyanurate, allylatedcyclohexyl di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate,dimethylol dicyclopentane di(meth)acrylate, ethylene oxide modifiedhexahydrophthalic acid di(meth)acrylate, tricyclodecane dimethanol(meth)acrylate, neopentyl glycol modified trimethylpropanedi(meth)acrylate, adamantane di(meth)acrylate or9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene; trifunctional acrylatessuch as trimethylolpropane tri(meth)acrylate, dipentaerythritoltri(meth)acrylate, propionic acid modified dipentaerythritoltri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxidemodified trimethylolpropane tri(meth)acrylate, trifunctional urethane(meth)acrylate or tris(meth)acryloxyethyl isocyanurate; tetrafunctionalacrylates such as diglycerin tetra(meth)acrylate or pentaerythritoltetra(meth)acrylate; pentafunctional acrylates such as propionic acidmodified dipentaerythritol penta(meth)acrylate; and hexafunctionalacrylates such as dipentaerythritol hexa(meth)acrylate, caprolactonemodified dipentaerythritol hexa(meth)acrylate or urethane (meth)acrylate(e.g. a reaction product of an isocyanate monomer and trimethylolpropanetri(meth)acrylate), and the like can be used.

As the polyfunctional acrylate, a compound termed a so-calledphoto-curable oligomer in the industry, such as urethane acrylate, epoxyacrylate, polyester acrylate or polyether acrylate and the like can beused. One or two or more of appropriate kinds among these compounds canbe selected and used.

The kind of the binder for forming the reddening-resistant layer or thevoid-containing layer (porous layer) is not limited to the above, andvarious other materials for optics may all be applied.

In order to ensure appropriate void characteristics satisfying desiredcharacteristics (thermal diffusivity (Equation 4), surfacecharacteristics (surface area ratio of AFM), infrared reflectance,visible light transmittance, SAXS characteristics, volume fractionand/or refractive index characteristics) in combination with hollowparticles, the polyfunctional acrylate from the above-described kindsmay be applied as the binder. That is, the binder may include a polymerof the polyfunctional acrylate. The polyfunctional acrylate is acompound having at least two or more polymerizable functional groups(acryloyl group, methacryloyl group, acryloyloxy group ormethacryloyloxy group). In another example, the number of the acrylicpolymerizable functional groups may be 3 or more, or may be 10 or less,9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, or 3or less. In forming a reddening-resistant layer in which thermaldiffusivity (Equation 4), surface characteristics (surface area ratio ofAFM), infrared reflectance, visible light transmittance, SAXScharacteristics, volume fraction and/or refractive index characteristicsare stably secured through the desired crosslinking degree and porecharacteristics, it is advantageous to apply a compound without anyhydroxy group and any ring structure (for example, an aromatic ringstructure or a dicyclopentadiene structure) as such a polyfunctionalacrylate. For the same reason, it is preferred that the hydroxy group orthe ring structure does not exist in the binder of thereddening-resistant layer (void-containing layer (porous layer)) or evenif it exists, the ratio thereof is limited. Also, in forming areddening-resistant layer in which thermal diffusivity (Equation 4),surface characteristics (surface area ratio of AFM), infraredreflectance, visible light transmittance, SAXS characteristics, volumefraction and/or refractive index characteristics are stably securedthrough the desired crosslinking degree and pore characteristics, it isadvantageous to use a compound having a molecular weight in a range ofabout 150 to about 1,000 g/mol as the polyfunctional acrylate. Inanother example, the molecular weight may be about 170 g/mol or more,about 190 g/mol or more, about 210 g/mol or more, about 230 g/mol ormore, about 250 g/mol or more, about 270 g/mol or more, or about 290g/mol or more, or may also be about 980 g/mol or less, about 960 g/molor less, about 940 g/mol or less, about 920 g/mol or less, about 900g/mol or less, about 880 g/mol or less, about 860 g/mol or less, about840 g/mol or less, about 820 g/mol or less, about 800 g/mol or less,about 780 g/mol or less, about 760 g/mol or less, about 740 g/mol orless, about 720 g/mol or less, about 700 g/mol or less, about 680 g/molor less, about 660 g/mol or less, about 640 g/mol or less, about 620g/mol or less, about 600 g/mol or less, about 580 g/mol or less, about560 g/mol or less, about 540 g/mol or less, about 520 g/mol or less,about 500 g/mol or less, about 480 g/mol or less, about 460 g/mol orless, about 440 g/mol or less, about 420 g/mol or less, about 400 g/molor less, about 380 g/mol or less, about 360 g/mol or less, about 340g/mol or less, about 320 g/mol or less, or about 300 g/mol or less orso. The binder may substantially comprise the polyfunctional acrylate asa main component in terms of more efficiently securing the desiredcharacteristics. Thus, the weight ratio of the polyfunctional acrylatein the binder may be about 50% or more, about 52% or more, about 54% ormore, about 56% or more, about 58% or more, about 60% or more, about 62%or more, about 64% or more, about 66% or more, about 68% or more, about70% or more, about 72% or more, about 74% or more, about 76% or more,about 78% or more, about 80% or more, about 82% or more, about 84% ormore, about 86% or more, about 88% or more, about 90% or more, about 92%or more, about 94% or more, about 96% or more, or about 98% or more orso, and this ratio may also be about 100% or less, or less than about100% or so. The ratio may be the ratio of the polyfunctional acrylate inthe binder, and for example, when the void-containing layer (porouslayer) is a layer comprising the binder and hollow particles, it may bea ratio based on the weight obtained by subtracting the hollow particlesfrom the total weight of the void-containing layer (porous layer).

As the hollow particles, for example, particles having a specificparticle size distribution may be used in order to satisfy each of theaforementioned physical properties. For example, as the hollowparticles, particles that in the weight cumulative curve of the particlesize distribution, the D10 particle diameter in the range of about 20 nmto about 50 nm or about 25 nm to about 50 nm, the D50 particle diameterin the range of about 50 nm to about 100 nm or about 55 nm to about 95nm, and the D90 particle diameter in the range of about 100 nm to about200 nm or about 110 nm to about 180 nm, respectively, can be applied.Here, when the total weight of the hollow particles is 100 weight, theD10, D50 and D90 particle diameters are values corresponding to about 10weight %, about 50 weight % and about 90 weight % of the maximum value(100 weight %), respectively, in the cumulative distribution graphindicating the weight for each particle diameter. Through theapplication of the particles having the particle diameter distributionas described above, the desired reddening-resistant layer can beeffectively formed.

In another example, the D10 particle diameter may be about 21 nm ormore, about 22 nm or more, about 23 nm or more, about 24 nm or more,about 25 nm or more, about 26 nm or more, about 27 nm or more, about 28nm or more, about 29 nm or more, about 30 nm or more, about 31 nm ormore, or about 32 nm or more, or may also be about 49 nm or less, about48 nm or less, about 47 nm or less, about 46 nm or less, about 45 nm orless, about 44 nm or less, about 43 nm or less, about 42 nm or less,about 41 nm or less, about 40 nm or less, about 39 nm or less, about 38nm or less, about 37 nm or less, about 36 nm or less, about 35 nm orless, about 34 nm or less, or about 33 nm or less or so.

In another example, the D50 particle diameter may be about 56 nm ormore, about 57 nm or more, about 58 nm or more, about 59 nm or more,about 60 nm or more, about 61 nm or more, or 62 nm or more, or may alsobe about 99 nm or less, about 98 nm or less, about 97 nm or less, orabout 96 nm or less, about 95 nm or less, about 94 nm or less, about 93nm or less, about 92 nm or less, about 91 nm or less, about 90 nm orless, about 89 nm or less, about 88 nm or less, about 87 nm or less,about 86 nm or less, about 85 nm or less, about 84 nm or less, about 83nm or less, about 82 nm or less, about 81 nm or less, about 79 nm orless, about 78 nm or less, about 77 nm or less, about 76 nm or less,about 75 nm or less, about 74 nm or less, about 73 nm or less, about 72nm or less, about 71 nm or less, or about 70 nm or less or so.

In another example, the D90 particle diameter may be about 111 nm ormore, about 112 nm or more, about 113 nm or more, about 114 nm or more,about 115 nm or more, about 116 nm or more, about 117 nm or more, about118 nm or more, about 119 nm or more, about 120 nm or more, or about 121nm or more, about 122 nm or more, or 123 nm or more, or may also beabout 179 nm or less, about 178 nm or less, about 177 nm or less, about176 nm or less, about 175 nm or less, about 174 nm or less, about 173 nmor less, about 172 nm or less, about 171 nm or less, about 170 nm orless, about 169 nm or less, about 168 nm or less, about 167 nm or less,about 166 nm or less, about 165 nm or less, about 164 nm or less, about163 nm or less, about 162 nm or less, about 161 nm or less, about 160 nmor less, about 159 nm or less, about 158 nm or less, about 157 nm orless, about 156 nm or less, about 155 nm or less, about 154 nm or less,about 153 nm or less, about 152 nm or less, about 151 nm or less, about150 nm or less, about 149 nm or less, about 148 nm or less, about 147 nmor less, about 146 nm or less, about 145 nm or less, about 144 nm orless, about 143 nm or less, about 142 nm or less, about 141 nm or less,about 140 nm or less, about 139 nm or less, about 138 nm or less, about137 nm or less, about 136 nm or less, about 135 nm or less, about 134 nmor less, about 133 nm or less, about 132 nm or less, about 131 nm orless, about 130 nm or less, about 129 nm or less, about 128 nm or less,about 127 nm or less, or about 126 nm or less or so.

As the hollow particles, particles that the pore size corresponds to thevoid size may be applied. Thus, the pore size may be in the range ofabout 0.5 nm to about 100 nm.

In another example, the pore size may be about 1 nm or more, about 2 nmor more, about 3 nm or more, about 4 nm or more, about 5 nm or more,about 6 nm or more, about 7 nm or more, about 8 nm or more, about 9 nmor more, about 10 nm or more, about 11 nm or more, about 12 nm or more,about 13 nm or more, about 14 nm or more, about 15 nm or more, about 16nm or more, about 17 nm or more, about 18 nm or more, about 19 nm ormore, about 20 nm or more, about 21 nm or more, about 22 nm or more,about 23 nm or more, about 24 nm or more, about 25 nm or more, about 26nm or more, about 27 nm or more, about 28 nm or more, about 29 nm ormore, about 31 nm or more, about 32 nm or more, about 33 nm or more,about 34 nm or more, about 35 nm or more, about 36 nm or more, about 37nm or more, or about 38 nm or more, or may also be about 99 nm or less,about 98 nm or less, about 97 nm or less, about 96 nm or less, about 95nm or less, about 94 nm or less, about 93 nm or less, about 92 nm orless, about 91 nm or less, about 90 nm or less, about 89 nm or less,about 88 nm or less, about 87 nm or less, about 86 nm or less, about 85nm or less, about 84 nm or less, about 83 nm or less, about 82 nm orless, about 81 nm or less, about 79 nm or less, about 78 nm or less,about 77 nm or less, about 76 nm or less, about 75 nm or less, about 74nm or less, about 73 nm or less, about 72 nm or less, about 71 nm orless, about 69 nm or less, about 68 nm or less, about 67 nm or less,about 66 nm or less, about 65 nm or less, about 64 nm or less, about 63nm or less, about 62 nm or less, about 61 nm or less, about 59 nm orless, about 58 nm or less, about 57 nm or less, about 56 nm or less,about 55 nm or less, about 54 nm or less, about 53 nm or less, about 52nm or less, about 51 nm or less, about 50 nm or less, about 49 nm orless, about 48 nm or less, about 47 nm or less, about 46 nm or less, orabout 45 nm or less or so.

Various kinds of hollow particles may be applied without particularlimitation as long as they may have the characteristics as above andexhibit the aforementioned characteristics (thermal diffusivity(Equation 4), surface characteristics (surface area ratio of AFM),infrared reflectance, visible light transmittance, SAXS characteristics,volume fraction and/or refractive index characteristics).

For example, as the hollow particles, organic particles in which theshell portion is made of an organic substance, inorganic particles inwhich it is made of an inorganic substance and/or organic-inorganicparticles in which it is made of an organic-inorganic substance, and thelike may be used. Such particles may be exemplified by acrylic particlessuch as PMMA (poly(methyl methacrylate)), epoxy particles, nylonparticles, styrene particles and/or copolymer particles of styrene/vinylmonomers, and the like, or inorganic particles such as silica particles,alumina particles, indium oxide particles, tin oxide particles,zirconium oxide particles, zinc oxide particles and/or titaniaparticles, and the like, but are not limited thereto.

The reddening-resistant layer or the void-containing layer (porouslayer) may comprise the hollow particles in a ratio of about 5 weight %or more. In another example, the ratio may be about 10 weight % or more,about 15 weight % or more, about 20 weight % or more, about 25 weight %or more, about 30 weight % or more, about 35 weight % or more, about 40weight % or more, about 45 weight % or more, about 50 weight % or more,about 55 weight % or more, about 60 weight % or more, about 65 weight %or more, about 70 weight % or more, about 75 weight % or more, about 80weight % or more, about 85 weight % or more, about 90 weight % or more,about 95 weight % or more, about 100 weight % or more, about 105 weight% or more, about 110 weight % or more, about 115 weight % or more, about120 weight % or more, about 125 weight % or more, about 130 weight % ormore, about 135 weight % or more, about 140 weight % or more, about 145weight % or more, about 150 weight % or more, about 155 weight % ormore, about 160 weight % or more, about 165 weight % or more, about 170weight % or more, about 175 weight % or more, or about 180 weight % ormore. In another example, the ratio may also be about 9,000 weight % orless, about 8,000 weight % or less, about 7,000 weight % or less, about6,000 weight % or less, about 5,000 weight % or less, about 4,000 weight% or less, about 3,000 weight % or less, about 2,000 weight % or less,about 1,000 weight % or less, about 900 weight % or less, about 800weight % or less, about 700 weight % or less, about 600 weight % orless, about 500 weight % or less, about 400 weight % or less, about 300weight % or less, about 250 weight % or less, about 240 weight % orless, about 230 weight % or less, about 220 weight % or less, about 210weight % or less, or about 200 weight % or less or so.

The ratio of the hollow particles may be adjusted according to thedesired characteristics. In one example, the reddening-resistant layeror the void-containing layer (porous layer) may comprise only the hollowparticles as the particles. That is, in such an example, thereddening-resistant layer or the void-containing layer (porous layer)may not comprise so-called solid particles. Accordingly, the desiredcharacteristics of the reddening-resistant layer or the void-containinglayer (porous layer) can be implemented more appropriately.

The reddening-resistant layer or the void-containing layer (porouslayer) may comprise any additive known in the art, if necessary, inaddition to the above components. Such an additive may be exemplified byhardeners or initiators for the binder, antioxidants, ultravioletstabilizers, ultraviolet absorbers, colorants, antifoams, surfactantsand/or plasticizers, and the like.

The thickness of the reddening-resistant layer or the void-containinglayer (porous layer) may be controlled for expression of the desiredreddening-resistance ability. For example, the reddening-resistant layeror the void-containing layer (porous layer) may have a thickness ofabout 200 nm or more. In this thickness range, the desiredreddening-resistant ability can be effectively expressed. In anotherexample, the thickness may also be about 250 nm or more, about 300 nm ormore, about 350 nm or more, about 400 nm or more, about 450 nm or more,about 500 nm or more, about 550 nm or more, about 600 nm or more, about650 nm or more, about 700 nm or more, about 750 nm or more, about 800 nmor more, about 850 nm or more, or about 900 nm or more or so. The upperlimit of the thickness is not particularly limited. In general, thethicker the reddening-resistant layer is, the better the effect ofpreventing, alleviating, reducing, suppressing and/or delaying heat isimproved. Therefore, the upper limit of the thickness of thereddening-resistant layer or the void-containing layer (porous layer)may be selected in consideration of the thickness required for theoptical laminate, and the like, without particular limitation, as longas the effect of preventing, alleviating, reducing, suppressing and/ordelaying heat is ensured. In one example, the thickness of thereddening-resistant layer or the void-containing layer (porous layer)may also be about 3,000 nm or less, about 2,900 nm or less, about 2,800nm or less, about 2,700 nm or less, about 2,600 nm or less, about 2,500nm or less, about 2,400 nm or less, about 2,300 nm or less, about 2,200nm or less, about 2,100 nm or less, about 2,000 nm or less, or about1,950 nm or less or so.

The position of the reddening-resistant layer in the optical laminatemay also be controlled to ensure the desired reddening-resistantperformance.

The reddening-resistant layer may be a layer included separately in theoptical laminate, or may be a layer implemented by forming voids in alayer (e.g., an adhesive layer or a pressure-sensitive adhesive layer)already present in the optical laminate.

The position of the reddening-resistant layer in the optical laminatemay be controlled for the purpose, i.e. prevention, alleviation,reduction, suppression and/or delay of the reddening.

For example, the reddening-resistant layer may be located as close aspossible to the optical functional layer which is the main cause of thereddening in the optical laminate. That is, the distance between thereddening-resistant layer and the optical functional layer in theoptical laminate can be controlled. Here, the distance may be theshortest interval, the maximum interval or the average interval betweenthe facing surfaces of the reddening-resistant layer and the opticalfunctional layer. In one example, the distance between thereddening-resistant layer and the optical functional layer may be withinabout 90 μm, within about 85 μm, within about 80 μm, within about 75 μm,within about 70 μm, within about 65 μm, within about 60 μm, within about55 μm, within about 50 μm, within about 45 μm, within about 40 μm,within about 35 μm, within about 30 μm, within about 25 μm, within about20 μm, within about 15 μm, within about 10 μm, within about 5 μm, withinabout 1 μm, within about 0.9 μm, within about 0.8 μm, within about 0.7μm, within about 0.6 μm, within about 0.5 μm, within about 0.4 μm,within about 0.3 μm, or within about 0.2 μm. The case where the opticalfunctional layer and the reddening-resistant layer are most closelylocated is the case where the two layers are in contact with each other,and in this case, the distance is 0 μm. Therefore, the lower limit ofthe distance is 0 μm. In another example, the distance may be about 0.01μm or more, about 0.02 μm or more, about 0.03 μm or more, about 0.04 μmor more, about 0.05 μm or more, about 0.09 μm or more, or about 0.1 μmor more or so.

This reddening-resistant layer may be disposed at a position that doesnot form the outermost surface of the optical laminate. That is, thereddening-resistant layer may not be the outermost layer of the opticallaminate. This positioning may be required to express thereddening-resistant characteristics of the optical laminate and/oroptical functional layer.

In another example, the optical laminate comprises an additional layertogether with the reddening-resistant layer and the optical functionallayer, where the reddening-resistant layer may be located between theoptical functional layer and the additional layer. FIG. 1 is one exampleof such a layer configuration, which shows the case where the additionallayer (30), the reddening-resistant layer (20) and the opticalfunctional layer (10) are sequentially formed. Here, the additionallayer may be a protective film, a pressure-sensitive adhesive layer, anadhesive layer, a hard coating layer, an antireflection layer, aretardation layer or a brightness enhancement layer, and the like, ormay be a cover glass to be described below, but is not limited thereto.

By such arrangement, the optical laminate of the present application mayexhibit somewhat high surface reflectance. That is, thereddening-resistant layer of the present application can act to lowerthe reflectance in its configuration, but since such areddening-resistant layer does not exist on the surface, the surfacereflectance of the optical functional layer may be somewhat higherunless a separate antireflection layer or the like is formed. Forexample, the optical laminate may have reflectance of about 2% or more.Here, the reflectance may be reflectance or average reflectance forlight in a visible light region, for example, any one wavelength in arange of approximately 380 nm to 780 nm, or wavelengths in apredetermined region in the range or the entire region. In anotherexample, the reflectance may be about 2.5% or more, about 3% or more,about 3.5% or more, or about 4% or more, or may also be about 10% orless, about 9% or less, about 8% or less, about 7% or less, about 6% orless, or about 5% or less or so.

By such arrangement, the reddening phenomenon of the optical functionallayer and/or the optical laminate can be effectively prevented,alleviated, reduced, suppressed and/or delayed.

The optical laminate may comprise various other layers as long as theoptical laminate comprises the reddening-resistant layer and the opticalfunctional layer.

Such a layer may be exemplified by, for example, a protective film forthe optical laminate, a pressure-sensitive adhesive layer, an adhesivelayer, a retardation film, a hard coating layer or a low reflectionlayer, and the like. The layers may also be the above-describedadditional layers.

As the type of the additional layer, a general configuration known inthe art may be applied. For example, as the protective film, a resinfilm having excellent transparency, mechanical strength, thermalstability, moisture barrier properties or isotropy, and the like may beused, and an example of such a film may be exemplified by a celluloseresin film such as a TAC (triacetyl cellulose) film, a polyester film, apolyether sulfone film, a polysulfone film, a polycarbonate film, apolyamide film, a polyimide film, a polyolefin film, an acrylic film, acyclic polyolefin film such as a norbornene resin film, a polyarylatefilm, a polystyrene film, a polyvinyl alcohol film, and the like.Furthermore, in addition to the protective layer in the form of a film,a cured resin layer obtained by curing a thermosetting or photocurableresin such as (meth)acrylic series, urethane series, acrylic urethaneseries, epoxy series or silicone series may also be applied as theprotective film. Such a protective film may be formed on one side orboth sides of the optical functional layer.

As the retardation film, a general material may be applied. For example,a monoaxially or biaxially stretched birefringent polymer film or analignment film of a liquid crystal polymer or a polymerized layer of apolymerizable liquid crystal compound, and the like may be applied. Thethickness of the retardation film is also not particularly limited.

The protective film or the retardation film as described above may beattached to the optical functional layer or the like by an adhesive orthe like, where such a protective film or the like may be subjected toeasy adhesion treatment such as corona treatment, plasma treatment,primer treatment or saponification treatment. In addition, when theprotective film is attached to the optical functional layer or thereddening-resistant layer, a hard coat layer, a low reflection layer, ananti-reflection layer, an anti-sticking layer, a diffusion layer or ahaze layer, and the like may be present on the side opposite to thesurface of the protective film to which the optical functional layer orthe reddening-resistant layer is attached.

In addition to the protective film or the retardation film, for example,various elements such as a reflective plate or a semi-transmissive platemay also be present in the optical laminate, where the kind thereof isnot particularly limited.

For the adhesion of each layer in the optical laminate, an adhesive maybe used. The adhesive may be exemplified by an isocyanate-basedadhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive,vinyl series latex series or water-based polyester, and the like, but isnot limited thereto. As the adhesive, a water-based adhesive may begenerally used, but a solventless photocurable adhesive may also be useddepending on the type of the film to be attached.

The optical laminate may comprise a pressure-sensitive adhesive layerfor adhesion with other members such as a liquid crystal panel or acover glass. A pressure-sensitive adhesive for forming thepressure-sensitive adhesive layer is not particularly limited, and forexample, it may be appropriately selected from those that an acrylicpolymer, a silicone-based polymer, a polyester, a polyurethane, apolyamide, a polyether, or a polymer such as fluorine series or rubberseries is used as a base polymer, and used. To the exposed surface ofsuch a pressure-sensitive adhesive layer, a release film may betemporarily attached and covered for the purpose of the contaminationprevention, etc., until it is provided to practical use.

Such an optical laminate may have various forms of structures. Forexample, FIG. 2 is a structure in which the reddening-resistant layer(20) is introduced in the structure of the polarizing plate which is themost basic optical laminate. That is, the basic polarizing plate has astructure in which a protective film (301) is attached to at least oneside of the polarizing layer (100), wherein the reddening-resistantlayer (20) may be positioned between the polarizing layer (100) and theprotective film (301). In the structure of FIG. 2, an adhesive or apressure-sensitive adhesive may be used for bonding each layer (100, 20,301). In one example, the reddening-resistant layer (20) of FIG. 2 maybe a separate layer, or itself may be the adhesive or thepressure-sensitive adhesive. That is, hollow particles or the like maybe introduced into the adhesive or the pressure-sensitive adhesive toform a void-containing layer (porous layer) acting as thereddening-resistant layer.

In FIG. 2, the protective film (302) is also attached to the bottom ofthe polarizing layer (100), that is, the surface opposite to thereddening-resistant layer (20), but this protective film (302) may beomitted or another kind of layer (for example, the retardation film orthe cured resin layer, and the like, as described above) may be attachedthereto. For example, a pressure-sensitive adhesive layer may be formedon the bottom of the protective film (302) present on the surfaceopposite to the reddening-resistant layer (20), that is, on the surfaceopposite to the surface of the protective film (302) toward thepolarizing layer (100), or a pressure-sensitive adhesive layer may beformed instead of the protective film (302).

FIG. 3 is, as a modified structure, a case where two protective films(301, 302) exist on one side of the polarizing layer (100) and areddening-resistant layer (20) exists between the protective films (301,302). In this case, a pressure-sensitive adhesive or an adhesive may beapplied to the adhesion of the layer, where the reddening-resistantlayer (20) may also be the pressure-sensitive adhesive or the adhesive.In such a structure, the details of the protective film (303) existingon the bottom of the polarizing layer (100) are the same as those of theprotective film (302) existing on the bottom of the polarizing layer(100) in the structure of FIG. 2.

FIGS. 2 and 3 are one example of the present application, where theoptical laminate of the present application may be composed of variousstructures in addition to these.

The present application also relates to a display device comprising theoptical laminate. The type of the display device may vary withoutparticular limitation, which may be, for example, a known LCD (liquidcrystal display) or OLED (organic light emitting display), and the like,and in such a display device, the optical laminate may be applied by aconventional method.

In particular, the optical laminate is effectively applied to a displaydevice comprising a so-called cover glass.

Such a device typically comprises a cover glass and an optical laminateattached to the cover glass by a so-called OCA (optical clear adhesive)or OCR (optical clear resin), and the like, where the laminate of thepresent application may be applied as the optical laminate. Accordingly,the display device comprises a cover glass and an optical laminateattached to the cover glass, wherein the optical laminate may comprise:the optical functional layer; and a reddening-resistant layer formed onat least one side of the optical functional layer, where thereddening-resistant layer may be located between the cover glass and theoptical functional layer.

In general, a display device comprising a cover glass is applied toapplications such as vehicle navigation, where the reddening phenomenonis more problematic due to the cover glass having a high thermalconductivity.

However, the optical laminate of the present application can be appliedto the device of the above structure to solve the above problem.

The specific structure of the display device is not particularly limitedas long as the optical laminate of the present application is applied,which may follow a known structure.

Advantageous Effects

The present application can provide an optical laminate that does notcause a so-called reddening phenomenon even when driven or maintainedunder extremely harsh conditions (e.g., very high temperatureconditions), or a porous layer applied thereto.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1 to 3 are diagrams for explaining exemplary structures of opticallaminates of the present application.

MODE FOR INVENTION

Hereinafter, the polarizing layer and the like will be described in moredetail with reference to examples according to the present application,and the like, but the scope of the present application is not limitedthereto.

Hereinafter, the respective physical properties of the polarizing layerand the like were measured in the following manners.

1. Measurement of Thickness

The thicknesses of the polarizing layer and the porous layer, and thelike can be measured by applying a TEM (transmission electronmicroscopy) instrument. After photographing the cross-section of thepolarizing layer or the porous layer with the TEM instrument, thethickness of the relevant layer can be confirmed from the photographedimage. In this example, Hitachi's H-7650 product was used as the TEMinstrument.

2. Measurement of Particle Size Distribution and Pore Size of HollowParticles

The particle size distribution of the hollow particles was measuredusing Otsuka Electronics' ELSZ-2000 equipment. In addition, the particlediameters and pore sizes of the hollow particles were measured byapplying a TEM (transmission electron microscopy) instrument. In thisexample, Hitachi's H-7650 product was used as the TEM instrument. Theparticle diameters and pore sizes were obtained, respectively, byoptionally selecting 50 hollow particles after photographing (10000times magnification) the cross-section of the porous layer in eachoptical laminate (polarizing plate) produced in Examples and the likeusing the TEM instrument, and the arithmetic means were taken asrepresentative values of the particle diameter and pore size.

3. CIE Color Coordinate Measurement

Color coordinates were measured using a JASCO V-7100 spectrophotometer.The JASCO V-7100 spectrophotometer is an instrument that after rotatingthe absorption axis of the measurement target polarizing plate from 0degrees to 360 degrees with respect to the absorption axis of thepolarizer built into the relevant instrument to measure the colorcoordinates (TD color coordinates) at the point where the transmittanceis minimum and rotating the absorption axis of the measurement targetpolarizing plate 90 degrees clockwise again at the point where thetransmittance is minimum to measure the color coordinates (MD colorcoordinates), the representative values of the color coordinates arederived based on the respective measured values. Color coordinatesdescribed in Examples of this specification are color coordinates thatare confirmed by the JASCO V-7100 spectrophotometer.

4. Measurement of Transmittance and Reflectance

The single transmittance of the polarizing plate, and the like weremeasured using a JASCO V-7100 spectrophotometer. The JASCO V-7100spectrophotometer is an instrument that the transmittance of thepolarizing plate, and the like are measured in a range of 380 to 780 nmto derive representative values for the wavelength range, and in thisexample, the transmittance identified on the JASCO V-7100spectrophotometer has been described.

5. Measurement of Weight Ratio of Potassium (K) and Zinc (Zn) inPolarizing Layer

The weight ratio of potassium (K) and zinc (Zn) present in thepolarizing layer was measured in the following manner. First, 0.1 g orso of the polarizing layer was dissolved in an aqueous solution ofnitric acid (2 mL) at a concentration of about 65 weight % at roomtemperature (about 25° C.), followed by diluting it to 40 mL withdeionized water, and then the weights of potassium (K) and zinc (Zn)contained in the polarizing layer were measured, respectively, usingICP-OES (Optima 5300).

6. Thermal Diffusivity Evaluation of Porous Layer

The thermal diffusivity of the porous layer was measured in thefollowing manner. The thermal diffusivity was evaluated in a state wherethe porous layer was formed on a TAC (triacetyl cellulose) film(manufactured by Hyosung, PG601F) having a thickness of approximately 60μm or so in the manner described in the following examples. At thistime, the thickness of the porous layer is described in each example.Graphite coating was performed on the top and bottom of the laminate ofthe TAC film/porous layer. The graphite coating was formed usingCRAMLIN's GRAPHITE product. The product was a product that could begraphite-coated by a spray method, and the relevant product was sprayedon the top (surface of the porous layer) and the bottom (TAC film) ofthe laminate once or so, and then dried to form a graphite layer.Thereafter, the thermal diffusivity was measured using NETZSCH's LFA 457MicroFlash product. The thermal diffusivity was measured based on atemperature of 95° C., which was confirmed through the temperaturetransfer from one graphite surface to the other graphite surface. Insuch a manner, the thermal diffusivity of the laminate (porous layer/TACfilm) was evaluated, and in each example, the relative ratio of thethermal diffusivity of the laminate relative to the TAC film wasdescribed.

7. Infrared Reflectance Evaluation of Porous Layer

The infrared reflectance of the porous layer was confirmed by thefollowing method. The infrared reflectance was evaluated in a statewhere a porous layer was formed on a TAC (triacetyl cellulose) filmhaving a thickness of approximately 60 μm or so in the manner describedin the following examples. At this time, the thickness of the porouslayer is described in each example. A black tape (black PET film fromTOMOEGAWA) was attached to the bottom (the surface of the film on whichthe porous layer was not formed) of the TAC film in the laminate of theporous layer/TAC film to perform darkening treatment, and the averagereflectance in a wavelength region of 800 to 1300 nm was measured in thereflectance mode using SHIMADZU's Solidspec 3700 equipment. If theinstrument was used, the reflectance for the wavelength range atintervals of 1 nm could be confirmed in the range of 800 nm to 1300 nm,and in this example, the arithmetic mean value of the reflectance foreach wavelength was taken as the representative value of the infraredreflectance.

8. Small Angle X Ray Scattering (SAXS) Evaluation of Porous Layer

The small angle X-ray scattering evaluation of the porous layer wasperformed in the following manner. The evaluation was performed in astate where the porous layer was formed on a TAC (triacetyl cellulose)film having a thickness of approximately 60 μm or so in the mannerdescribed in the following examples. At this time, the thickness of theporous layer is described in each example. A test specimen ismanufactured by cutting the laminate of the TAC film/porous layer sothat the width and length are each about 1 cm or so. The porous layer ofthe test specimen was irradiated with X-rays having a wavelength of0.0733 nm at a distance of 4 m apart to obtain scattering intensityaccording to the scattering vector. The measurement was performed on aPohang accelerator 4C beamline, and X-rays having a vertical size of0.023 mm or so and a horizontal size of 0.3 mm or so were used. 2D marCCD was used as a detector. After the scattered 2D diffraction patternimage was obtained, it was calibrated using the sample-to-detectordistance obtained through the standard sample(polyethylene-block-polybutadiene-block-polystyrene, SEBS), and thescattering intensity according to the scattering vector (q) wasconverted through the circular average. At this time, the scatteringvector was obtained according to the following equation A.

q=4π sin(θ/λ)  [Equation A]

In Equation A, q is the scattering vector, θ is a value ½ times thescattering angle (unit: degree), and λ is the wavelength of theirradiated X-rays (unit: angstrom (Å)).

9. Cauchy Parameter Measurement

The refractive index and Cauchy parameter of the porous layer wereperformed in the following manner. The evaluation was performed in astate where the porous layer was formed on a TAC (triacetyl cellulose)film having a thickness of approximately 60 μm or so in the mannerdescribed in the following examples. At this time, the thickness of theporous layer is described in each example. For the reddening-resistantlayer of the laminate (porous layer/TAC film), the characteristics wereevaluated using the equipment (J. A. Woollam Co. M-2000). For the porouslayer, linearly polarized light was measured in a wavelength range of380 nm to 1,000 nm at an incident angle of 70 degrees by applying theequipment. The measured linearly polarized light data (ellipsometry data(Psi (Ψ), delta (Δ)) were subjected to fitting by using the CompleteEASE software so that the MSE of the Cauchy model of Equation 1 belowwas 25 or less, and n(λ), A, B and C of Equation 6 below were obtained.In the fitting process, the Roughness function was applied with on(range of −20˜50 nm).

$\begin{matrix}{{n(\lambda)} = {A + \frac{B}{\lambda^{2}} + \frac{C}{\lambda^{4}}}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

In Equation 6, n (2) is the refractive index at a wavelength of 2 nm.

10. Evaluation of Surface Area Ratio

The surface area ratio of the reddening-resistant layer (void-containinglayer (porous layer)) was measured using an AFM instrument (atomic forcemicroscope, Park Systems, XE7). A sample manufactured by cutting alaminate having a reddening-resistant layer (void-containing layer(porous layer)) formed on one side of a TAC film so that the width andlength are 1 cm, as described in examples, was fixed on the stage of theinstrument using a carbon tape, and the measurement was performed. As aprobe (tip) for the measurement, PPP-NCHR 10 (Force Constant: 42 N/m,Resonance Frequency 330 kHz) was used. Measurement conditions are asfollows.

<Measurement Conditions>

x-scan size: 1 μm

y-scan size: 1 μm

Scan rate: 0.7 to 1 Hz

Z Servo Gain: 1

Set Point: 10 to 15 nm

Data measured under these conditions were flattened under the followingconditions using the XEI program.

<Flattening Conditions>

Scope: Line

Orientation: X and Y axis

Regression Order: 1

After flattening, the surface area ratio was extracted from the Regiontab in the XEI program.

Production Example 1. Production of Polarizing Layer (A)

A PVA (poly(vinyl alcohol)) film (Japan Synthetic Co., Ltd., M3004L)having a thickness of about 30 μm was immersed in a dye solution at 28°C. containing 0.2 weight % of iodine (I₂) and 2.5 weight % of potassiumiodide (KI) for 60 seconds and subjected to dyeing. Subsequently, thedyed PVA film was immersed in an aqueous solution at 35° C.(crosslinking solution) containing 1 weight % of boron and 3 weight % ofpotassium iodide (KI) for 60 seconds and subjected to crosslinking.Thereafter, the crosslinked PVA film was stretched at a draw ratio of5.4 times using an inter-roll stretching method. The stretched PVA filmwas immersed in ion-exchanged water at 25° C. for 60 seconds and washed,and immersed in an aqueous solution at 25° C. containing 2 weight % ofzinc nitrate and 5 weight % of potassium iodide (KI) for 30 seconds.Thereafter, the PVA film was dried at a temperature of 80° C. for 60seconds to produce a PVA polarizing layer. The final thickness of theproduced polarizing layer was about 12 μm or so, the potassium contentwas about 0.9 weight %, and the zinc content was about 0.3 weight %. Inaddition, 1/(1+0.025d/R) was about 0.9. Here, d is the thickness of thepolarizing layer (12 μm), and R is the ratio (K/Zn) of the weight ratio(K, unit: weight) of the potassium component contained in the polarizinglayer and the weight ratio (Zn, unit: weight) of the zinc component.

Production Example 2. Production of Porous Layer (A) Material

A porous layer was produced by applying TMPTA (trimethylolpropanetriacrylate) as a binder and applying hollow silica particles. As thehollow silica particles, particles having D10, D50 and D90 particlediameters of 32.1 nm, 62.6 nm and 123.4 nm, respectively, were used. Inthis case, after forming the porous layer, the average of the pore sizesmeasured by TEM was approximately 38.3 nm or so, and the particlediameter was approximately 53 nm or so. The binder, the hollow silicaparticles, a fluorine-containing compound (RS-90, DIC) and an initiator(Irgacure 127, Ciba) were diluted in MIBK (methyl isobutyl ketone) as asolvent in a weight ratio of 31:65:0.1:3.9 (binder: hollow silicaparticles: fluorine-containing compound: initiator) based on the solidcontent to prepare a coating solution.

Production Example 3. Production of Porous Layer (B) Material

A porous layer was produced by applying TMPTA (trimethylolpropanetriacrylate) as a binder and applying hollow silica particles. As thehollow silica particles, particles having D10, D50 and D90 particlediameters of 39.9 nm, 70.6 nm and 126.0 nm, respectively, were used. Inthis case, after forming the porous layer, the average of the pore sizesmeasured by TEM was approximately 44.1 nm or so, and the particlediameter was approximately 61 nm or so. The binder, the hollow silicaparticles, a fluorine-containing compound (RS-90, DIC) and an initiator(Irgacure 127, Ciba) were diluted in MIBK (methyl isobutyl ketone) as asolvent in a weight ratio of 55.1:40:1.1:3.8 (binder: hollow silicaparticles: fluorine-containing compound: initiator) to prepare a coatingsolution.

Production Example 4. Production of Porous Layer (C) Material

A porous layer was produced by applying PETA (pentaerythritoltriacrylate) as a binder and applying hollow silica particles. As thehollow silica particles, particles having D10, D50 and D90 particlediameters of 39.9 nm, 70.6 nm and 126.0 nm, respectively, were used. Inthis case, after forming the porous layer, the average of the pore sizesmeasured by TEM was approximately 44.1 nm or so, and the particlediameter was approximately 61 nm or so. The binder, the hollow silicaparticles, a fluorine-containing compound (RS-90, DIC) and an initiator(Irgacure 127, Ciba) were diluted in MIBK (methyl isobutyl ketone) as asolvent in a weight ratio of 76.5:20:0.5:3.0 (binder: hollow silicaparticles: fluorine-containing compound: initiator) to prepare a coatingsolution.

Production Example 5. Production of Resin Layer (A) Material

A resin layer material was produced by applying PETA (pentaerythritoltriacrylate) as a binder and applying solid silica particles withoutapplying hollow silica particles. As the solid silica particles,particles having D10, D50 and D90 particle diameters of 43.1 nm, 69.9 nmand 125.8 nm, respectively, were used. In this case, after forming theresin layer, the particle diameter measured by TEM was approximately 60nm or so. The binder, the solid silica particles, a fluorine-containingcompound (RS-90, DIC) and an initiator (Irgacure 127, Ciba) were dilutedin MIBK (methyl isobutyl ketone) as a solvent in a weight ratio of31:65:0.1:3.9 (binder: solid silica particles: fluorine-containingcompound: initiator) to prepare a coating solution.

Example 1

A COP (cycloolefin polymer) film (manufacturer: Zeon) having a thicknessof approximately 30 μm or so as a protective film was attached to thepolarizing layer (A) obtained in Production Example 1 by applying ageneral optical water-based adhesive layer (thickness: 100 nm).Separately, a porous layer was formed on a TAC (triacetyl cellulose)film (manufactured by Hyosung, PG601F) having a thickness ofapproximately 60 μm or so. The porous layer was formed by coating theporous layer (A) material of Production Example 2 with a Mayer barthereon, drying it at 60° C. or so for 1 minute or so, and thenirradiating it with ultraviolet rays (252 mJ/cm²) to have a finalthickness of about 450 nm or so. The surface area ratio measured for thesurface opposite to the surface of the formed porous layer in contactwith the TAC film was in a level of about 0.148. Subsequently, theporous layer in the laminate of the porous layer and the TAC film wasattached to the polarizing layer (A) in the laminate of the COP film andthe polarizing layer (A) as produced above with the same water-basedadhesive agent (thickness: 100 nm). Subsequently, an acrylicpressure-sensitive adhesive layer was formed on the bottom of thepolarizing plate to produce a polarizing plate (optical laminate) havinga structure in which the protective film (COP film), the adhesive layer,the polarizing layer, the adhesive layer, the porous layer, theprotective film (TAC film) and the pressure-sensitive adhesive layerwere sequentially laminated.

Example 2

A polarizing plate was produced in the same manner as in Example 1,except that the porous layer was changed. The porous layer was formed bycoating the coating solution of Production Example 3 on the same TACfilm as that of Example 1 using a Mayer bar, drying it at 60° C. for 1minute, and then irradiating it with ultraviolet rays (252 mJ/cm²) tohave a final thickness of 600 nm. The surface area ratio measured forthe surface opposite to the surface of the formed porous layer incontact with the TAC film was in a level of about 0.0359. A polarizingplate was manufactured in the same manner as in Example 1, except thatthe porous layer formed in the above manner was applied.

Example 3

A polarizing plate was produced in the same manner as in Example 1,except that the porous layer was changed. Here, the porous layer wasformed in the same manner as in Example 1 using the coating material ofProduction Example 4, but it was formed to have a final thickness ofapproximately 950 nm or so. The surface area ratio measured for thesurface opposite to the surface of the formed porous layer in contactwith the TAC film was in a level of about 0.109. A polarizing plate wasmanufactured in the same manner as in Example 1, except that the porouslayer formed as above was applied.

Comparative Example 1

A polarizing plate was produced in the same manner as in Example 1,except that the porous layer was not applied.

Comparative Example 2

A resin layer was formed on a TAC (triacetyl cellulose) film (Hyosung,PG601F) having a thickness of approximately 60 μm or so. The resin layerwas formed by coating the resin layer (A) material of Production Example5 with a Mayer bar, drying it at 60° C. for 1 minute or so, and thenirradiating it with ultraviolet rays (252 mJ/cm²) to have a finalthickness of about 450 nm or so. The surface area ratio measured on thesurface opposite to the surface of the formed resin layer in contactwith the TAC film was in a level of about 0.01. A COP (cycloolefinpolymer) film (manufacturer: Zeon) having a thickness of approximately30 μm or so as a protective film was attached to the polarizing layer(A) obtained in Production Example 1 by applying a general opticalwater-based adhesive layer (thickness: 100 nm). The formed resin layerwas attached to the polarizing layer (A) in the laminate of the COP filmand the polarizing layer (A) as produced above with the same water-basedadhesive agent (thickness: 100 nm) as above. Subsequently, an acrylicpressure-sensitive adhesive layer was formed on the bottom of thepolarizing plate to produce a polarizing plate (optical laminate) havinga structure in which the protective film (COP film), the adhesive layer,the polarizing layer, the adhesive layer, the resin layer, theprotective film (TAC film) and the pressure-sensitive adhesive layerwere sequentially laminated.

The characteristics of the porous layer formed in each of the aboveexamples were summarized and described in Table 1 below (in the case ofComparative Example 1, the porous layer was not formed, and inComparative Example 2, the characteristics of the resin layer weredescribed).

TABLE 1 Porous layer IR Scattering Thermal Cauchy Parameter coefficientReflectance vector diffusivity A B C (%) (nm⁻¹) relative ratio Example 11.331 0.00287 0.000101 3.34 0.132 60% 2 1.335 0.00363 0.000244 3.760.128 62% 3 1.332 0 0.000347 2.71 0.13 63% Comparative Example 2 1.5150.000864 0.0000151 1.8 0.211 92% IR Reflectance: Infrared reflectanceScattering vector: Scattering vector in which a peak is identified on alog value graph of scattering intensity of small angle X-ray scatteringThermal diffusivity: Relative ratio of thermal diffusivity of porouslayer/TAC film laminate to thermal diffusivity of TAC film at 95° C.

After the heat-proof test was performed for Examples and ComparativeExamples above, the single transmittance and color coordinate a* changeamount were evaluated and the results were summarized and described inTable 2 below. Here, the heat-proof test was performed by contacting thetop and bottom whole surfaces of the polarizing plate produced in eachof Examples or Comparative Examples with soda lime glass (SEWON TECH)having a thickness of about 1.1 mm or so and laminating them, and thenmaintaining the resultant at 105° C. for 250 hours. In addition, afterobserving whether or not the reddening phenomenon was confirmed with thenaked eye, the results were summarized as NG in the case that it wasconfirmed and PASS in the case that it was not confirmed, and describedin Table 2 below (in Table 2 below, the unit of transmittance is %).

TABLE 2 Holding at 105° C. for 250 hours a* Initial Naked Transmittancechange Transmittance a* Transmittance a* eye change amount amountExample 1 41.3 −1.47 40 −0.87 PASS −1.3 0.6 2 41.5 −2.05 40.6 −1.95 PASS−0.9 0.1 3 41.3 −1.66 40.5 −1.56 PASS −0.8 0.1 Comparative 1 41.8 −1.831.8 2 NG −10 3.8 Example 2 41.7 −2.7 32.9 2.5 NG −8.8 5.2

1. An optical laminate, comprising: a polarizing layer; and a porouslayer formed on at least one side of the polarizing layer, wherein thepolarizing layer comprises zinc component, and wherein an absolute valueof a change in an amount of color coordinate a* of CIE L*a*b* accordingto Equation 1 is 2 or less:Δa*=a* _(a) −a* _(i)  [Equation 1] wherein Δa* is the change in theamount of the color coordinate a*, a*_(a) is a color coordinate a* ofthe optical laminate after maintaining the optical laminate at 105° C.for 250 hours under a state where both top and bottom surfaces of theoptical laminate come in contact with glass substrates, and a*, is acolor coordinate a* of the optical laminate before maintaining theoptical laminate at 105° C. for 250 hours.
 2. The optical laminateaccording to claim 1, wherein the polarizing layer is an iodine-basedpolarizing layer.
 3. The optical laminate according to claim 1, whereinthe polarizing layer satisfies Equation 3:0.70 to 0.97=1/(1+0.025d/R)  [Equation 3] wherein d is a thickness (μm)of the polarizing layer, and R is a ratio (K/Zn) of a weight ratio (K,unit: weight %) of potassium component in the polarizing layer withrespect to a weight ratio (Zn, unit: weight %) of zinc component in thepolarizing layer.
 4. The optical laminate according to claim 1, whereinthe porous layer satisfies Equation 4:H _(L)≤0.9×H _(P)  [Equation 4] wherein H_(L) is a thermal diffusivityof a laminate of a polymer film and the porous layer formed on one sideof the polymer film, and H_(P) is the thermal diffusivity of the polymerfilm.
 5. The optical laminate according to claim 1, wherein the porouslayer comprises a surface having a surface area ratio of 0.02 or more asmeasured by an atomic force microscope.
 6. The optical laminateaccording to claim 1, wherein the porous layer has reflectance of 2% ormore with respect to light having a wavelength of 800 nm to 1300 nm. 7.The optical laminate according to claim 1, wherein the porous layerexhibits at least one peak within a scattering vector range of 0.06 to0.209 nm⁻¹ in a log value graph of scattering intensity of small angleX-ray scattering.
 8. The optical laminate according to claim 1, whereinan A value satisfying Equation 6 of the porous layer is 1.5 or less, a Bvalue satisfying Equation 6 of the porous layer is from 0 to 0.01 and aC value satisfying Equation 6 of the porous layer is from 0 to 0.001:[Equation 6]${n(\lambda)} = {A + \frac{B}{\lambda^{2}} + \frac{C}{\lambda^{4}}}$wherein, n(λ) is the refractive index of the porous layer at awavelength of λ, and λ is any one wavelength in a range of 300 to 1800nm.
 9. The optical laminate according to claim 1, wherein the porouslayer comprises a binder and hollow particles.
 10. The optical laminateaccording to claim 9, wherein the binder comprises a polymer derivedfrom a polyfunctional acrylate having 2 to 10 polymerizable functionalgroups.
 11. The optical laminate according to claim 9, wherein thehollow particles have a D10 particle diameter in a range from 25 to 50nm, a D50 particle diameter in a range from 50 to 95 nm and a D90particle diameter in a range from 100 nm to 200 nm in a weightcumulative curve of particle size distribution.
 12. The optical laminateaccording to claim 1, wherein the porous layer does not comprise solidparticles.
 13. The optical laminate according to claim 1, wherein theporous layer has a thickness of 200 nm or more.
 14. The optical laminateaccording to claim 1, wherein the porous layer does not form a surfaceof an outermost layer in the optical laminate.
 15. The optical laminateaccording to claim 1, wherein an additional layer is further comprisedand wherein the porous layer is between the additional layer and thepolarizing layer.
 16. The optical laminate according to claim 1, whereinthe distance between the porous layer and the polarizing layer is 90 μmor less.